Atto 8 Fault Codes

Below is a complete list of known fault codes (DTC) for the Atto 8 in AU. Each code includes its meaning, severity level, and links to real owner repair cases where available. Use this list to diagnose warning lights and understand potential repair costs before visiting a service centre.

All known diagnostic trouble codes for the Atto 8 in AU — meanings, severity levels, and what to do.

914Total codes

B1108›
For the BYD Song MAX (2017–2019), DTC B1108 indicates a short circuit in the PM2.5 air quality detection module (dust sensor) or its wiring harness. The sensor uses laser scattering to detect in-cabin and outside PM2.5 concentrations and transmits data to the HVAC ECU via the LIN bus or an analog signal. Short circuit conditions include: 1) Sensor power supply wire (+5V/+12V) shorted to ground 2) Signal wire shorted to power or ground 3) Short circuit in the sensor's internal photoelectric detection circuit This fault prevents the automatic climate control from switching between fresh air and recirculation based on air quality. The system enters fail-safe mode (typically forced recirculation). Severe short-circuit current can destroy the HVAC ECU sampling circuit. The system classifies this as a Level 3 severe fault and restricts vehicle operation to prevent electrical fires or controller damage. For other BYD models (such as the Qin EV, E5, and Song DM), B1108 indicates a driver-side sunload sensor fault, reflecting differences in DTC definitions across models.
B110811›
This DTC indicates a short circuit in the air conditioning system PM2.5 air quality sensor (rapid detector). Specifically, abnormal continuity exists between the sensor power supply circuit or signal output circuit and body ground or battery positive. This causes the control module (ACU/air conditioning controller) to detect abnormal current or a voltage signal outside the valid range (typically 0V or supply voltage). The PM2.5 sensor monitors internal and external particulate concentrations, providing the data the automatic air conditioning system uses to switch between fresh air and recirculation modes. A short circuit disables the air quality monitoring function. This fault may force the air conditioning system into recirculation protection mode and trigger related thermal management system faults, as the air conditioning system acts as a key actuator in vehicle thermal management. In severe cases, the short circuit current can damage the internal sampling circuit of the air conditioning controller or overheat the wiring harness.
B1109›
DTC B1109 indicates an open circuit in the communication line between the air conditioning system PM2.5 air quality sensor (dust concentration sensor) and the air conditioning control unit (AC ECU), or an open circuit within the sensor internal circuitry. Typically located in the air conditioning intake duct, this sensor monitors real-time PM2.5 particle concentration inside and outside the vehicle. It provides data to the automatic air conditioning system for intelligent switching between fresh air and recirculation modes and for controlling the air purification device. During an open circuit fault, the AC ECU cannot receive the air quality signal, triggering the system fail-safe mode. Symptoms typically include failure of the automatic recirculation function, abnormal air purification indicator light operation, or abnormal air quality data displayed on the air conditioning panel. Severe cases may compromise the cabin environment control strategy, but do not directly affect vehicle driving safety.
B110913›
DTC B110913 indicates an open signal circuit for the PM2.5 rapid detector (in-cabin air quality sensor). This sensor typically mounts inside the air conditioning system intake duct. It monitors in-cabin PM2.5 concentration in real time and provides data to the automatic air conditioning system for intelligent control of the air purification function. The BYD diagnostic protocol uses sub-code '13' to specifically indicate an open signal circuit. Although this fault theoretically affects a comfort feature, BYD Qin series vehicles classify it as a Level 3 (severe) fault. This classification occurs because the air conditioning system interacts with the battery thermal management system (e.g., monitoring battery cooling intake air quality). The fault can disable the automatic air conditioning mode and prevent the air purification function from operating. In extreme cases, it affects the battery compartment intake air quality assessment, triggering the 'repair immediately' strategy.
B110A›
This DTC indicates interrupted CAN bus communication or abnormal data between the air conditioning control unit (ACU) and the PM2.5 air quality sensor. The PM2.5 sensor monitors particulate concentration inside and outside the vehicle and provides the basis for purification control in the automatic air conditioning system. The ACU triggers this fault if it fails to receive a valid CAN message from the sensor within the specified period (usually 100-500 ms), if message verification fails, or if the signal frame times out. Although this fault does not affect vehicle driving safety, it disables the automatic air purification function. The air conditioning system cannot automatically switch between recirculation and fresh air modes or activate the air purification mode based on air quality. A persistent fault may restrict the thermal management strategy.
B110A02›
DTC B110A02 indicates the thermal management master control unit (HVAC ECU) or body control module (BCM) failed to receive valid CAN data frames from the PM2.5 air quality sensor over consecutive communication cycles (typically 500ms per cycle). The sensor typically mounts at the HVAC unit air inlet or behind the glove box and transmits real-time particulate concentration data (unit: μg/m³) to the HVAC controller via the CAN bus. The fault is essentially a communication link layer timeout. Potential causes include physical layer wiring faults, sensor power supply failures, sensor internal MCU lockup, or CAN network topology damage. Although this non-critical fault does not directly affect driving safety, it disables the intelligent air purification strategy and the automatic fresh air/recirculation switching function. In extreme cases, it triggers a thermal management system degraded mode, limiting compressor power or fixing the air flap position.
B110B07›
This fault code indicates abnormal operation of the internal air pump (sampling pump) in the PM2.5 air quality detection module. The PM2.5 detector uses the laser scattering principle to measure particulate concentration and requires a built-in air pump to draw ambient air into the detection chamber at a constant flow rate. The ECU sets this code when it detects an open or short in the air pump drive circuit, abnormal current (stall or free-running), or abnormal speed feedback. This fault causes the automatic air conditioning system to lose air quality sensing capability, preventing automatic switching between fresh air and recirculation modes. The instrument cluster air quality display may show '--' or a fixed value, but the fault does not affect the vehicle powertrain or basic air conditioning cooling and heating functions.
B160C-00›
DTC B160C-00 indicates the SRS (Supplemental Restraint System) control module detects the driver frontal airbag (steering wheel airbag module) igniter (squib) circuit resistance exceeds the calibrated upper limit. Normal BYD Qin series airbag igniter resistance is 2.0-3.0 Ω. The ECU triggers this fault when it detects the resistance continuously exceeds the threshold (typically >5 Ω or an open circuit). This hard fault means the airbag may fail to deploy normally (fail-safe mode) or delay deployment during a collision, severely compromising driver passive safety. Poor contact, wiring oxidation, a partial open circuit, or igniter aging causes the abnormal increase in circuit resistance.
B110B›
DTC B110B indicates a fault in the internal air pump (sampling pump) of the PM2.5 air quality detector. This pump draws cabin or outside air into the PM2.5 sensor detection chamber, enabling the laser scattering sensor to measure real-time particulate matter concentration. The air conditioning controller (or BCM) sets this DTC upon detecting an open or short circuit in the pump drive circuit, or abnormal current caused by a seized pump motor. This fault disables the "Green Clean" system, causes the instrument cluster air quality display to read abnormally or disappear, and disables the automatic fresh air/recirculation switching function. It does not affect the vehicle powertrain or core thermal management functions.
B110C›
DTC B110C indicates a functional failure of the internal laser diode in the PM2.5 air quality detection module. The sensor operates on the laser scattering principle. The laser diode emits a 650nm or 780nm laser beam. Airborne particulate matter passing through the detection chamber scatters this light. A photodiode array receives the scattered light and converts it into electrical signals. An algorithm then calculates the PM2.5 mass concentration. Laser diode failure (open circuit, light degradation below threshold, or driver circuit fault) prevents the sensor from establishing the detection optical path. The system continuously outputs abnormal concentration values (typically fixed at 0 μg/m³ or 999 μg/m³). This causes the air conditioning thermal management system to lose automatic air quality closed-loop control, preventing automatic recirculation, negative ion generator linkage, and air purification reminders. This fault does not directly affect drive motor thermal management or power battery cooling. However, the system classifies this as a Level 3 severe fault because the sensor acts as a core environmental sensing component for the air conditioning system. False readings can also force the HVAC module into continuous high-power operation or cause abnormal air flap adjustment. In some models (e.g., Song MAX), the sensor communicates with the air conditioning control unit via the LIN bus. A laser assembly fault can cause abnormal bus sleep current.
B110C09›
DTC B110C09 indicates a driver-side seat belt pretensioner circuit fault, specifically an open circuit, short to ground, or abnormal resistance (standard resistance 1.8-2.5Ω). This fault relates to the Supplemental Restraint System (SRS). The Airbag Control Unit (ACU) triggers this code upon detecting driver-side pretensioner circuit voltage or resistance outside the specified threshold. The pretensioner is a critical safety device operating in conjunction with the airbag. During a collision, the gas generator tightens the seat belt to eliminate slack between the webbing and the occupant. This fault forces the airbag system into fail-safe mode and continuously illuminates the instrument panel airbag warning light. This condition can prevent the pretensioner from deploying during a collision, significantly increasing occupant injury risk.
B121209›
DTC B121209 indicates an abnormality in the PTC (Positive Temperature Coefficient) heater drive control unit, specifically a driver module fault. This fault involves the high-voltage control system. Causes include IGBT power module failure, driver circuit board malfunction, high-voltage interlock (HVIL) failure, or abnormal current/voltage sampling. The PTC heater is a core component for EV cabin heating and battery thermal management. This fault prevents cabin heating and disables battery heating. In low-temperature environments, it degrades battery charge/discharge performance and reduces driving range. When this fault occurs, the BMS or thermal management controller cuts off the PTC high-voltage power supply to protect the system.
B110D›
DTC B110D indicates a failure of the Photoelectric Receiving Module in the in-cabin PM2.5 detection system. In the BYD Song MAX Green Purification System, the PM2.5 sensor operates on the laser scattering principle: a laser diode emits a light beam of a specific wavelength through an air sample, and airborne particles scatter the light. The Photoelectric Receiving Module (usually containing a photodiode or photomultiplier tube) captures the scattered light signal and converts it into an electrical signal. When this module fails, the system cannot accurately detect the in-cabin PM2.5 concentration. This failure disables the automatic air purification function, disrupts the A/C automatic fresh air/recirculation switching function, and may trigger an air quality detection fault on the instrument cluster. Although this fault does not directly affect vehicle power or core thermal management functions, it disables the intelligent A/C purification system and impairs in-cabin air quality management during severe smog conditions.
B110D09›
DTC B110D09 indicates a failure of the internal photoelectric receiving module in the PM2.5 rapid detector (laser particulate sensor). The sensor operates on the laser scattering principle: a laser diode emits a beam to illuminate an air sample. Suspended particulate matter produces scattered light. The photoelectric receiving module (typically a high-sensitivity photodiode or photomultiplier tube) captures this light and converts it into an electrical signal. The signal processing circuit then calculates the PM2.5 concentration. DTC B110D09 specifically refers to a fault in the module receiving the scattered light. Possible causes include photoelectric component aging or burnout, a signal amplification circuit fault, A/D conversion module damage, or an internal open circuit. This fault prevents the Green Air Purification System from obtaining accurate air quality data, disabling the automatic air purification mode and the A/C automatic fresh air/recirculation switching function. Although this fault typically does not affect the powertrain or driving safety, it disables the thermal management system's environmental adaptive control strategy. The system classifies this fault as severe because abnormal communication between the sensor and the A/C control module can trigger cascading faults.
B110E09›
This DTC indicates a functional failure of the temperature and humidity sensing module in the PM2.5 air quality rapid detection system. This module integrates into the PM2.5 detector and monitors ambient air temperature and relative humidity in real time. The system uses these readings to compensate and correct the light-scattering measurement data from the laser particulate sensor, as temperature and humidity changes significantly affect PM2.5 detection accuracy. An abnormal analog signal or digital communication interruption causes this fault. This prevents the air conditioning controller from obtaining accurate ambient temperature and humidity parameters, disabling the automatic air purification, negative ion generator linkage, and air quality display functions. Although the system classifies this as a "severe" fault, it only affects comfort features and does not impact the powertrain or driving safety. The vehicle can travel a short distance to a repair facility.
B121013›
This DTC indicates an open circuit in the left heat sink temperature sensor of the thermal management system PTC (Positive Temperature Coefficient) heater. This sensor, typically an NTC (Negative Temperature Coefficient) thermistor, monitors the real-time surface temperature of the PTC ceramic heating element to prevent overheating. The ECU determines an open circuit when it detects a continuously high sensor signal voltage (typically the 5V reference voltage returning without voltage division). This fault triggers a protective shutdown of the PTC heater, resulting in no warm air in the cabin. In extreme cases, if the PTC overheats and the failed sensor cannot provide feedback, it may trigger a high-voltage safety cut-off or risk thermal runaway.
B110F›
DTC B110F indicates an actuator circuit failure in the solenoid valve (switching valve) inside the PM2.5 air quality detection module. This solenoid valve controls the physical switching of the sampling air passage to select the channel for in-cabin or outside air sampling. The air conditioning controller (ACU) triggers this code if it issues a switching command but fails to detect the solenoid valve current feedback or position confirmation signal (such as Hall sensor feedback), or if it detects a coil short or open circuit. This failure prevents the system from accurately comparing the PM2.5 concentration difference between the cabin and outside air, disables Auto Clean mode, and may force the air conditioning system into a protective recirculation mode.
B161A-00›
Fault code B161A-00 indicates the front passenger frontal airbag ignition circuit resistance is 0 ohms. This condition signifies a short to ground in the airbag circuit or an internal short circuit within the airbag module. Normal airbag system resistance is typically 2-3 ohms. A 0-ohm resistance allows current to bypass the airbag inflator and flow directly from the positive terminal to ground. Consequently, the Airbag Control Unit (ACU) determines the airbag risks unintended deployment or failure to deploy. The system then illuminates the airbag warning lamp and disables the airbag. Repair procedures for certain BYD models (such as the Qin, Tang, and Song series) may also log this fault code as a Left Front Impact Sensor communication fault or wiring short circuit. Verify the exact definition using the specific model year and SRS software version. Regardless of the definition, this constitutes a critical safety system fault that prevents the airbag system from protecting occupants during a collision.
B110F09›
DTC B110F09 indicates a High Voltage Interlock Loop (HVIL) fault, contrary to some materials that incorrectly label it as a "PM2.5 rapid tester solenoid valve failure". The HVIL serves as a critical safety protection mechanism on BYD new energy vehicles. The system triggers this code when it detects compromised high-voltage circuit integrity, such as a loose connector, an open wiring harness, or an abnormal service disconnect switch. Upon logging this fault, the BMS immediately opens the high-voltage relays and disables high-voltage power-up to prevent electric shock. As a hard safety fault, it prevents the vehicle from entering READY mode or causes a sudden loss of power while driving.
B121111›
This DTC indicates a short to ground in the PTC (Positive Temperature Coefficient) heater left heat sink temperature sensor signal circuit, or an internal sensor short circuit. BYD Qin series vehicles typically integrate this sensor into the PTC heater assembly to monitor heater core temperature and prevent overheating. During a short circuit, the air conditioning controller detects an abnormally low voltage signal (near 0V) and triggers protection logic to cut PTC power, disabling the heating function. Because the PTC heater draws high operating current (up to tens of amperes), temperature monitoring failure risks overheating or fire. Therefore, the system classifies this as a severe fault (Level 3).
B121309›
DTC B121309 indicates a fault in the PTC (Positive Temperature Coefficient) heating assembly. The PTC heater is a core high-voltage component in the electric vehicle thermal management system. Operating at 320V-750V DC, it heats the coolant to provide cabin heating and low-temperature battery pack preheating. Trigger conditions for this DTC include: PTC unit insulation resistance falling below the safety threshold (typically <1MΩ/V); abnormal PTC operating current (overcurrent, open circuit, or short circuit); communication timeout between the PTC controller and the air conditioning controller/thermal management controller (CAN signal lost); abnormal PTC temperature sensor (NTC) signal (open circuit or short to power/ground); or high-voltage interlock loop (HVIL) continuity detection failure. Upon fault detection, the system cuts off the high-voltage power supply to the PTC, disabling the air conditioning heating function and limiting the defrost function. In severe cold conditions, this can impair driver visibility and battery thermal management efficiency, though it typically does not affect vehicle driveability.
B121619›
DTC B121619 indicates the actual operating current in the Positive Temperature Coefficient (PTC) ceramic heater high-voltage circuit exceeds the safety threshold set by the control module (typically 10A-12A, depending on vehicle configuration). The PTC is the core component of the air conditioning heating system in battery electric and plug-in hybrid vehicles. It uses high-voltage DC power (typically 320V-750V) to heat the ceramic element, which then heats the coolant to provide warm air to the passenger compartment and preheat the traction battery in low-temperature conditions. Excessive current indicates a circuit insulation failure causing a short to ground, internal PTC ceramic plate breakdown, controller power device (IGBT/MOSFET) shoot-through breakdown, or a high-voltage interlock circuit anomaly causing loss of controller regulation. This fault triggers the thermal management system high-voltage interlock protection, forcibly cutting off the PTC power supply and resulting in no cabin heat and loss of battery preheating functions. Failure to resolve this issue promptly can blow the high-voltage fuse or burn out the PTC heater. In extreme cases, a high-voltage arc could ignite the surrounding wiring harness.
B121809›
This DTC indicates a functional failure of the IGBT (Insulated Gate Bipolar Transistor) power module in the thermal management system, specifically the electric compressor or PTC heater controller. 'Uncontrolled, stuck on or stuck off' indicates the IGBT has lost gate control capability. A stuck-on state means the IGBT conducts continuously, creating a high-voltage short circuit risk or forcing the component to run continuously at full power. A stuck-off state means the IGBT cuts off completely, resulting in a loss of function. Typical causes include gate drive circuit damage (e.g., isolation driver chip or gate resistor faults), IGBT breakdown or open circuit, abnormal drive power supply (±15V supply failure), or abnormal PWM signal output from the control board MCU. In high-voltage environments, this fault can trigger overcurrent protection lockout, cause insulation faults, or induce thermal breakdown of the power module, posing a severe safety risk.
B12171C›
DTC B12171C indicates an abnormality in the internal +15V regulated power supply circuit of the thermal management controller (integrated into the electric A/C compressor controller or PTC heater controller). An internal isolated DC-DC converter module (typically utilizing a flyback or buck topology) generates this voltage from the 12V low-voltage system to power the IGBT drive circuit, phase current sensors, NTC temperature sampling circuit, and internal operational amplifiers. Fault conditions include voltage exceeding the upper threshold (typically >16.5V), dropping below the lower threshold (typically <13.5V), or an excessive voltage ripple factor (>5%). This fault restricts compressor drive capability (initiating power derating mode), reduces PTC heating efficiency, or disables thermal management system closed-loop control. It typically does not trigger a high-voltage interlock disconnection, allowing the vehicle to operate in limp-home mode.
B121A09›
DTC B121A09 indicates a functional failure of the No. 1 IGBT (Insulated Gate Bipolar Transistor) driver chip in the PTC (Positive Temperature Coefficient) heater controller. In BYD new energy vehicle thermal management systems, the PTC heater functions as a high-voltage electric heating component for cabin heating and power battery preheating. The IGBT module regulates heater power via PWM (Pulse Width Modulation) control. The driver chip serves as the key interface between the controller MCU and the power IGBT. It converts low-voltage logic signals into isolated high-voltage pulses (typically ±15V or 0-15V) to drive the IGBT gate. Fundamentally, this fault indicates the driver chip cannot generate or transmit the gate drive signal. Possible causes include internal chip damage, abnormal driver power supply, IGBT module fault feedback, or communication interruption. This fault prevents the PTC heater from starting (no warm air) or causes power control loss. In extreme cases, it may cause IGBT breakdown and short circuits, triggering high-voltage system protection and posing safety risks. Therefore, the system classifies it as a severe fault (Level 3).
B121B09›
This fault code indicates a functional failure of the No. 2 IGBT (Insulated Gate Bipolar Transistor) driver chip in the thermal management system PTC (Positive Temperature Coefficient) heater controller. In BYD Qin series vehicles, the PTC heater uses IGBTs for PWM power modulation to control heating output. "2#" usually refers to the second drive circuit in a dual-channel PTC control system or the driver IC for the second unit of the IGBT module. Fundamentally, the driver IC fails to generate a normal gate drive signal, preventing the IGBT from switching on and off correctly. This directly disables the PTC heater, resulting in no warm air from the air conditioning and battery heating function failure. Extreme cases may cause an IGBT shoot-through short circuit, creating a high-voltage safety risk. Underlying faults such as overtemperature, overcurrent, or power supply abnormalities typically accompany driver chip failures.
B121C09›
This fault code indicates a functional failure of the No. 3 IGBT (Insulated Gate Bipolar Transistor) driver chip in the thermal management system. In BYD Qin series new energy vehicles, the A/C PTC (Positive Temperature Coefficient) heater uses an IGBT module for high-power PWM modulation control, where "3#" refers to the third-phase drive channel or the third IGBT unit. The IGBT driver chip converts low-voltage logic signals from the controller into high-voltage, high-frequency pulse signals to drive the IGBT gate, precisely regulating PTC heater power (0-100% duty cycle control). This fault occurs when the driver chip fails to output the normal gate drive voltage (typically a +15V/-8V push-pull signal), or when the chip’s internal desaturation protection or overcurrent protection triggers abnormally, preventing the IGBT from conducting or forcing it to remain off. This directly causes partial or complete PTC heater failure, affecting cabin heating. In low-temperature environments, it also disables battery pack preheating, potentially triggering a vehicle thermal management fault and limiting power output.
B121D09›
DTC B121D09 indicates a functional failure of the No. 4 IGBT (Insulated Gate Bipolar Transistor) driver chip in the thermal management system's PTC (Positive Temperature Coefficient) heater assembly. In the air conditioning system of BYD Qin series models, the PTC heater uses multiple IGBT power modules with PWM (Pulse Width Modulation) control to provide stepless adjustment of heating power. This DTC indicates a malfunction in the No. 4 channel IGBT driver integrated circuit (typically an isolated optocoupler driver or dedicated gate driver IC). Possible causes include drive signal loss, abnormal gate voltage, triggered IGBT overcurrent or overtemperature protection, or power transistor breakdown. This fault causes the PTC heater to partially or completely stop working, resulting in a loss of cabin heating function. This can compromise driving safety in cold environments. An IGBT short circuit may also trigger the high-voltage interlock protection, preventing high-voltage system activation or limiting power output.
B122013›
This DTC indicates an open circuit in the thermal management system right heatsink temperature sensor (NTC thermistor). In BYD Qin EV/DM models, this sensor typically mounts on the PTC heater heatsink or the motor controller (MCU) IGBT heatsink to monitor power device operating temperatures in real time. When sensor wiring breaks, the sensor fails, or the connector makes poor contact, the control module detects a voltage signal outside the valid range (typically because the 5V reference voltage fails to complete a circuit) and logs this fault. Because the system cannot accurately monitor the heatsink temperature, it triggers a thermal management protection strategy. This strategy may disable the PTC heater or limit motor power output. In extreme cases, power devices may overheat and fail, making this a severe fault.
B122111›
DTC B122111 indicates a short to ground or abnormally low signal circuit impedance in the air conditioning/thermal management system RHS Fin Temperature Sensor. This sensor is typically an NTC (negative temperature coefficient) thermistor with a normal operating voltage range of 0.5-4.5V. The ECU triggers this fault when the signal voltage remains below 0.1V (short-circuit threshold) for longer than a set time (typically 2-5 seconds). In Qin EV/Qin Pro DM models, this sensor mounts on the right-hand fin of the PTC heater assembly or at the heater core outlet to monitor the heater operating temperature and prevent overheating. A short circuit prevents the thermal management ECU from obtaining accurate temperature data. The ECU then triggers a protection mechanism that shuts down the PTC heater and restricts the air conditioning heating function. In extreme cases, this condition opens the high-voltage interlock and forces the vehicle into limp mode.
B122B11›
In DTC B122B11, "B" designates the Body control system, "122B" identifies the coolant temperature sensor, and "11" indicates a signal circuit short to ground per the BYD diagnostic protocol. The sensor mounts at the PTC heater outlet or in the motor cooling circuit. It utilizes an NTC (negative temperature coefficient) thermistor, where resistance decreases as temperature increases. The ECU sets this code when the sensor signal voltage remains below 0.1V, indicating a direct ground. A short circuit causes the ECU to read an extremely high temperature, as low NTC resistance corresponds to high heat. The thermal management system immediately enters protection mode. It forces the PTC heater off (disabling cabin heating) and may limit motor power to prevent overheating, classifying this as a Level 3 severe fault. This fault links to the air conditioning system because the PTC serves as the core EV cabin heating component, placing its temperature monitoring under the A/C thermal management subsystem.
B122A13›
DTC B122A13 indicates an open circuit fault in the thermal management system coolant temperature sensor circuit. In models such as the BYD Qin EV300, this sensor typically mounts in the PTC (Positive Temperature Coefficient) water heater or the battery thermal management circuit. It monitors coolant temperature to control heating power and battery thermal management strategies. An open circuit means the ECU detects a continuously high sensor signal voltage (typically near the 5V reference voltage) and cannot acquire the actual temperature signal. This fault forces the PTC heater into protection mode and halts operation, resulting in no warm air in the cabin. It may also affect the battery preheating function, restricting charging speed or preventing charging in low-temperature environments. In severe cases, the vehicle may trigger a thermal management system fault and enter limp mode.
B123098›
This DTC indicates the vehicle thermal management system detects the air conditioning PTC (Positive Temperature Coefficient) heater left heat sink temperature exceeds the safety threshold (typically >85-90°C). BYD Qin series vehicles use a zoned control architecture for the PTC heater; the left heat sink corresponds to the driver-side heater core heat exchange circuit. An abnormal rise in heat sink temperature indicates the coolant cannot effectively dissipate heat generated by the PTC. Possible causes include coolant circulation failure, internal heat accumulation within the PTC assembly, or an abnormal temperature monitoring circuit. Continued operation will cause thermal breakdown of the PTC ceramic elements, melt surrounding wiring harness insulation, or trigger a thermal runaway fire. Consequently, the system triggers a Level 3 severe fault protection strategy, disconnects the PTC high-voltage power supply, and disables vehicle drive to prevent irreversible damage.
B123398›
This DTC indicates the vehicle thermal management system detects the right heat sink (typically the PTC high-voltage heater module or power electronics cooling base) temperature exceeds the preset safety threshold (generally >85°C-95°C). As an active safety protection mechanism, the vehicle limits or cuts off the PTC heating function when triggered to prevent thermal runaway from damaging high-voltage components or causing a fire risk. The right heat sink typically corresponds to the right unit of the cabin PTC heater or a specific cooling module in the battery heating circuit. This abnormal temperature indicates insufficient cooling capacity in the cooling circuit or a faulty heating element.
B123698›
DTC B123698 indicates a range/performance fault in the position sensor circuit of the driver-side (left) Temperature Blend Door Actuator. This actuator sits inside the HVAC assembly and drives the blend door to adjust the hot/cold air mix ratio at the left air outlet (0% = full cold, 100% = full hot). The HVAC controller sets this DTC when it detects via the LIN bus or analog signal that the deviation between the actual actuator position and the target command exceeds the threshold (typically >10%), or the position sensor feedback voltage remains outside the normal range (0.5-4.5V) for a specified duration. This fault causes left-side temperature adjustment failure, locks the temperature at a single setting, produces abnormal gear slipping noise, or forces the HVAC system into protection mode. Note: Early service data may incorrectly label this as a coolant temperature fault. Current technical definitions and repair practices confirm a blend door actuator control circuit fault.
B123917›
The DTC definition varies by model year; rely on the diagnostic tool's actual description. For 2022–2024 BYD Seal, Han DM-i, Tang DM-p, and similar models, technical bulletin TSB-BYD-2023-B12-017 defines B123917 as "left seat horizontal adjustment motor position feedback circuit open/short to ground" within the Body control system. This indicates the voltage signal from the Hall-effect position sensor (built into the driver's seat horizontal adjustment motor) to the Seat Control Unit (SCU) exceeds the calibrated upper limit (normal: 0.5–4.5V; fault condition: >4.8V or short to ground detected). A failed sensor, a signal wire shorted to power, or a faulty SCU internal sampling circuit causes this condition. Symptoms include seat memory function failure, abnormal automatic return, or interrupted adjustment. However, early documentation for the 2017–2019 Qin EV300 and Qin Pro DM incorrectly labels this code as a thermal management system fault: "low-side voltage overvoltage" (abnormal A/C low-pressure sensor signal). Distinguish between these definitions during diagnosis.
B123A16›
This DTC indicates an undervoltage fault in the low-pressure side control circuit of the BYD new energy vehicle thermal management system. Specifically, the 12V low-voltage supply to the air conditioning system (electric compressor, PTC heater, or thermal management control module) drops below the normal operating threshold (generally below 9.5V or 80% of the system set value), or the A/C low-pressure sensor reference or signal voltage is abnormal. In models such as the Qin EV300 and Qin PRO DM, this fault causes insufficient power supply to the Thermal Management Module (TMM) or Air Conditioning Control Unit (ACU). This shortage can prevent the electric compressor from starting, limit PTC heater output, and disable battery cooling and heating functions. Although the vehicle remains drivable, A/C cooling and heating performance drops significantly. In extreme cases, high-voltage battery thermal management fails and triggers power limitation.
B123B17›
This DTC indicates that, in the thermal management system of a BYD new energy vehicle, the monitored voltage on the high-voltage side of the air conditioning compressor exceeds the system safety threshold (typically >420V DC; the specific threshold varies by vehicle calibration). In the electric scroll compressor system of BYD Qin series models, the "high-voltage side" specifically refers to the high-voltage DC bus voltage driving the compressor motor, not the refrigerant pressure. The Battery Management System (BMS) via the high-voltage interlock (HVIL) circuit, or the Air Conditioning Controller (ACU), triggers this protective DTC upon detecting an abnormally high voltage at the compressor inverter input. This fault forces the air conditioning compressor to shut down, resulting in a loss of cabin cooling. If the vehicle uses a battery liquid cooling system, this fault severely impairs the traction battery’s heat dissipation capability and may force the battery thermal management system to operate in a degraded mode.
B123C16›
This DTC indicates the electric air conditioning compressor (EAC) high-voltage power supply circuit detects an input voltage below the normal operating threshold (typically below 250V-300V, depending on the vehicle software version). In BYD thermal management systems, the high-voltage battery (300-750V DC) directly powers the electric compressor, and the controller monitors the high-voltage side voltage in real time. Upon detecting sustained undervoltage, the system limits or stops compressor operation to protect the compressor inverter module (IPM), causing air conditioning cooling/heating failure or degraded thermal management performance. BMS power limitations or insulation faults typically accompany this fault, which essentially indicates an abnormality in the high-voltage power distribution circuit or battery pack energy management.
B132012›
DTC B132012 indicates a short to power in the left front seat heater circuit (DTC structure: B13 = Seat Control Module (SCM) system, 20 = left front seat heater, 12 = short to power). The Seat Control Module triggers this code when it detects an abnormally low-resistance path between the heater pad circuit and the vehicle power supply (B+). This fault causes the seat heating function to fail, the heater pad to overheat, and may produce a burning smell. Severe cases can blow the associated fuse or damage the control module. This fault falls under the body electrical system and has no relation to the coolant temperature sensor described in the original documentation (Note: some reference materials contain classification errors; this is strictly a seat system fault).
B132013›
DTC B132013 is a specific fault within the thermal management/air conditioning subsystem (13) of the BYD body control system (B-Body). The '20' designates the battery coolant temperature sensor or a related thermal management temperature sensor, and '13' indicates an open circuit. This fault indicates the thermal management control unit (typically integrated into the Battery Management System (BMS) or air conditioning controller) detects a continuously high voltage on the coolant temperature sensor signal circuit (typically near the 5V reference voltage) and cannot obtain a valid temperature resistance signal. As a result, the thermal management system enters fail-safe mode. The system forcibly limits charge and discharge power, disables DC fast charging, and activates the maximum cooling strategy (high-speed fan and full-speed water pump operation). In extreme cases, the system triggers a 'powertrain fault' and prevents the vehicle from entering the Ready state to prevent overheating damage to the battery or drive motor caused by the loss of temperature monitoring.
B132112›
This fault code indicates a short to ground in the plate heat exchanger (PHE) outlet temperature sensor signal circuit, or an internal sensor short circuit. This sensor typically utilizes an NTC (negative temperature coefficient) thermistor to monitor the coolant or refrigerant temperature exiting the PHE, serving as a key feedback component for the thermal management system. The short circuit sends an abnormal voltage signal (typically near 0V) to the ECU, causing the system to falsely detect an extreme temperature state. This triggers the thermal management protection strategy, resulting in: forced electric compressor shutdown, battery cooling circuit interruption, restricted PTC heating function, or activation of the 'Power System Malfunction' reduced power mode. Continued driving may overheat the battery pack or drive motor due to the lack of effective temperature monitoring, creating a thermal runaway risk.
B132113›
This DTC indicates an open circuit in the thermal management system Plate Heat Exchanger (PHE) coolant outlet temperature sensor. The PHE is the core heat exchange component between the battery liquid cooling system and the air conditioning refrigerant system. The outlet temperature sensor monitors the post-exchange coolant temperature, providing a critical feedback signal for precise battery pack temperature control. An open circuit fault causes the ECU to receive an out-of-range high-voltage signal (typically near the 5V reference voltage), preventing the system from obtaining accurate outlet temperature data. This triggers thermal management system protection strategies, which may limit battery charge and discharge power, disable air conditioning cooling, or activate forced air cooling. Extreme cases pose a risk of battery thermal runaway. The sensor utilizes an NTC thermistor with a normal operating temperature range of -40°C to 150°C. During an open circuit, the resistance approaches infinity.
B132212›
This fault code indicates a short to power or short to ground in the signal circuit of the refrigerant pressure sensor at the plate heat exchanger (Chiller) outlet in the Battery Thermal Management System (BTMS). The plate heat exchanger is a key heat exchange component in the battery liquid cooling circuit. Its outlet pressure serves as a critical parameter for the system to evaluate refrigerant status and control electronic expansion valve opening and compressor speed. When a short circuit occurs in the sensor signal wire, the control unit (typically the battery manager or integrated thermal management controller) detects an abnormal voltage signal (near 0V or supply voltage), preventing accurate refrigerant pressure data acquisition. The system enters fail-safe protection mode and may limit battery charge and discharge power, disable the battery cooling function, or trigger a Level 1 or Level 2 fault warning. Long-term operation risks traction battery overheating and may trigger thermal runaway protection in extreme cases.
B132213›
This fault code indicates an open circuit in the signal circuit of the pressure/temperature sensor at the Plate Heat Exchanger (PHE) outlet. In the BYD heat pump thermal management system, the Plate Heat Exchanger is the core component for heat exchange between the refrigerant and the motor coolant. The outlet pressure sensor monitors the refrigerant pressure (or integrated temperature) after heat exchange, providing closed-loop control data for the Electronic Expansion Valve (EXV) and the electric compressor. An open circuit fault indicates the control unit (air conditioning controller or thermal management module) detects a continuous sensor signal voltage above 4.8V (typically corresponding to an unshunted 5V reference voltage). Without real-time pressure data, the system triggers thermal management protection mode. This mode disables the heat pump function, limits motor power output, and in extreme cases, prohibits high-voltage power-up to prevent heat exchanger overpressure damage or abnormal refrigerant circulation.
B132316›
This DTC indicates the 12V operating supply voltage of the thermal management system (specifically the air conditioning control unit or thermal management controller) falls below the 9V threshold. In the BYD new energy architecture, the low-voltage system has a nominal voltage of 12V (normal range 10.5V-14.5V). When the supply voltage drops below 9V, the controller’s internal microprocessor, sensor interface circuits, and power drive module fail to operate stably. This instability can cause abnormal air conditioning compressor control signals, inaccurate electronic expansion valve actuation, insufficient battery coolant pump speed, or a protective shutdown of the PTC heater. As a power supply fault, this condition does not directly trigger the high-voltage interlock, but it indirectly affects battery thermal management performance. In extreme cases, it can trigger battery over-temperature power derating protection.
B132317›
This DTC indicates the air conditioning system control unit or a thermal management-related module detects its operating supply voltage exceeds the 16V threshold (BYD low-voltage system rated voltage: 12V; normal operating range: 9–16V). This is an overvoltage protection fault. When the module detects an abnormal rise in supply voltage, it stores this DTC and may enter protection mode, limiting air conditioning or thermal management functions to prevent electronic component damage. Overvoltage typically stems from abnormal output from the low-voltage charging system (DC-DC converter), alternator voltage regulator failure (hybrid models), or abnormal power supply circuit impedance. Prolonged overvoltage may burn out the control module internal circuits or damage the compressor driver.
B132816›
This DTC indicates the Battery Thermal Management Electric Water Pump supply voltage falls below the system normal operating threshold (typically below 9V or 10.5V, depending on vehicle calibration). In the BYD Qin EV thermal management system, this water pump circulates coolant between the battery pack and the heat exchanger to maintain cell temperature within the optimal 15–35°C operating range. During an undervoltage fault, the pump may experience an abnormal speed drop, stop intermittently, or fail completely, reducing battery cooling and heating efficiency. Prolonged operation with this fault can trigger the BMS power limit protection strategy (reduced-power driving) and, in extreme cases, pose a risk of battery thermal runaway. The air conditioning controller (or thermal management controller) triggers this fault upon detecting an abnormal PWM feedback signal from the water pump or an abnormal power supply voltage.
B132817›
This fault code indicates the supply voltage or feedback voltage of the heat pipe electric water pump in the Battery Thermal Management System (BTMS) exceeds the calibrated threshold (typically exceeding 16V in the low-voltage system, or abnormal high-voltage sampling). In models like the BYD Qin EV, the VCU or Thermal Management Controller (TMS) drives this water pump via a PWM signal (100-900Hz). Upon fault trigger, the system records freeze-frame voltage data. Overvoltage may cause water pump drive MOSFET breakdown and motor winding insulation aging, triggering battery thermal management derating protection (limiting charge and discharge power). Prolonged overvoltage may cause insufficient battery pack heat dissipation, but typically does not affect driving safety before triggering overheat protection. Differentiate between genuine overvoltage (power supply system fault) and false overvoltage (sampling circuit or sensor fault).
B132971›
This DTC indicates the electric water pump in the battery thermal management circuit (typically located in the battery pack liquid-cooling circuit or battery heat pipe circulation branch) detects a locked rotor condition. Specifically, the pump control module detects the drive current continuously exceeding the threshold (typically 3-5 times the rated current) while the speed feedback signal remains at zero or extremely low, determining a mechanical rotor seizure. This is a hard fault. Upon triggering, the thermal management controller immediately cuts pump power to protect the drive circuit. Consequences include interrupted battery pack coolant circulation, causing loss of battery temperature control during fast charging and reduced heat pump air conditioning heating efficiency (if equipped with a water-source heat pump system). Continued operation may trigger BMS power derating protection or high-voltage system shutdown. The DTC suffix '71' typically serves as a subtype identifier indicating a persistent locked rotor condition rather than a momentary overload.
B132A00›
This fault code indicates the electric water pump in the battery thermal management system (typically integrated into the battery thermal pipe cooling circuit) is dry running. The system triggers this fault when the pump motor receives a PWM operating command from the TMS (Thermal Management Controller) or A/C controller and powers on to rotate, but the impeller fails to generate effective coolant flow. The system also triggers this fault if the actual speed detected by the speed feedback sensor (Hall effect sensor) deviates from the target speed by more than the threshold (typically >30%) for 5–10 seconds. This fault functions as flow abnormality protection. The condition can cause insufficient battery pack heat dissipation and excessive cell temperature differences, triggering reduced power operation (torque limiting). In extreme cases, it triggers a battery overheat warning. Causes include dry running due to a lack of coolant, impeller shaft breakage, magnetic coupling slip, cavitation, or seized bearings.
B1600-00›
This DTC indicates the SRS (Supplemental Restraint System) control unit (ACU) detects an open circuit or high resistance in the driver front airbag ignition circuit. The ACU continuously monitors the airbag module circuit resistance through its internal diagnostic circuit. Normal resistance is 2.0-2.4 Ω. Resistance exceeding the threshold (usually >6 Ω) or a completely open circuit triggers DTC B1600-00. The system then enters fail-safe mode and disables the driver-side airbag, preventing deployment during a collision. The instrument panel airbag warning lamp remains illuminated to alert the driver. Possible causes include the airbag module, clock spring (spiral cable), wiring harness connectors, or the ACU internal sampling circuit.
B1600›
DTC B1600 indicates the SRS (Supplemental Restraint System) control unit detects an open circuit or connection failure in the driver front airbag (steering wheel airbag) circuit. Specifically, electrical circuit resistance between the airbag control unit and the driver airbag assembly exceeds the standard range (normal: approx. 2-3Ω; fault: typically >10Ω or infinite). This hard-wired connection fault indicates the control unit continuously fails to establish effective communication with the driver airbag during vehicle self-test or driving. Upon triggering, the SRS enters fail-safe mode, illuminates the airbag warning lamp, and disables driver airbag deployment. In a collision, this airbag may fail to inflate normally, severely compromising passive safety performance. Some early BYD petrol models or specific powertrain systems define B1600 as "mixture too rich." However, based on current DTC information and applicable models (Yuan, Tang, Song, Qin series), this analysis focuses on the airbag system circuit fault.
B16001B›
DTC B16001B indicates the SRS (airbag) system detects a range/performance fault in the driver seat occupancy sensor (OCS - Occupant Classification System) signal circuit. Specifically, the ACU (Airbag Control Unit) receives a sensor resistance value outside the calibrated range (typically an open circuit, short circuit, or abnormal resistance), or the signal characteristics fail to match the expected logic. This film pressure sensor, located inside the driver seat cushion or on the inner side of the seat rail, monitors seat occupancy in real time to determine whether to allow full-power airbag deployment during a collision. If the system cannot confirm driver presence, it illuminates the airbag warning light and may enter a degraded protection mode (such as disabling airbag deployment or reducing deployment force), posing a severe safety hazard.
B1601-00›
DTC B1601-00 indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance path to body ground in the driver frontal airbag (DAB) ignition circuit. Under normal conditions, the airbag igniter circuit resistance measures 2.0-3.0 Ω, and the insulation resistance to ground exceeds 10 MΩ. Damaged wiring harness insulation, an internal clock spring short circuit, or a grounded connector terminal significantly reduces circuit resistance (typically below 1 Ω), causing the ECU to register a short-to-ground fault. This fault prevents the driver airbag from deploying during a collision (fail-safe mode) or, in extreme cases, causes unexpected deployment due to false triggering. As a critical passive safety hard fault, immediately remove the vehicle from service for repair.
B1601›
DTC B1601 indicates a short to ground in the driver frontal airbag (DAB) ignition circuit. In the BYD SRS (Supplemental Restraint System), this fault means damaged wire insulation in the circuit between the airbag control unit (ACU) and the driver airbag contacts the vehicle body ground, or an internal short to ground exists within the airbag inflator. This causes circuit resistance to drop well below the standard range (normally 2.0-3.0 Ω, approaching 0 Ω during a short circuit). When the ACU detects this abnormal drop in circuit impedance, it identifies a short-to-ground fault and triggers protection mode: the instrument cluster SRS warning light illuminates continuously, the system disables the driver airbag to prevent inadvertent deployment, and the airbag fails to deploy during a collision, severely compromising occupant safety.
B160111›
DTC B160111 indicates a short to ground in the driver frontal airbag (DAB) igniter circuit. The SRS (Supplemental Restraint System) airbag igniter utilizes a low-resistance circuit (typically 2.0–3.0Ω). The ACU (Airbag Control Unit) registers a short to ground when it detects circuit resistance below the threshold (<0.8Ω) or direct continuity to body ground. Wiring insulation failure or an internal component short circuit causes this fault, grounding the igniter circuit abnormally. Effects include: 1) the airbag may fail to deploy during a collision (current bypasses to ground); 2) electrostatic discharge or electromagnetic interference may cause unintended deployment in extreme cases; 3) the system enters fail-safe mode, disabling all airbag functions. This constitutes a Level 1 active safety system fault. Remove the vehicle from service immediately; the driver airbag serves as the final line of defense, and its failure drastically increases the risk of injury or fatality during an accident.
B1602-00›
This DTC indicates a short to power (positive) in the driver-side front airbag (steering wheel airbag) ignition circuit. Specifically, the airbag control unit (ACU/SRS ECU) detects abnormal continuity between the driver airbag ignition wiring harness (typically the W/L white-blue and G/R green-red wires) and the vehicle power supply. Resistance falls below the threshold (normal values exceed 1 MΩ; fault conditions may approach 0 Ω or display a voltage exceeding 1 V). This severe electrical fault in the airbag system poses two extreme risks: first, the short circuit can trigger unintended airbag deployment, injuring the driver; second, a continuous bypass of the airbag circuit prevents proper deployment during an actual collision. Potential fault locations include the clock spring (spiral cable), airbag module wiring harness, connectors, or inside the airbag ECU.
B1602›
DTC B1602 indicates a short to power in the driver frontal airbag (DAB) igniter circuit. In the BYD SRS (Supplemental Restraint System) architecture, the Airbag Control Unit (ACU) continuously monitors the circuit resistance of each airbag igniter (normally about 2-3 Ω) and its insulation status. When the ACU detects abnormal continuity between the driver airbag igniter wiring and the vehicle power supply (12V+) (resistance below the threshold, typically <10 kΩ for a short to power), it triggers this fault. This fault means the airbag may deploy unexpectedly while driving (a serious safety risk) or fail to deploy properly in a collision because the power supply clamps the circuit. The fault may originate in the clock spring (spiral cable), airbag wiring harness, connector, or the ACU internal driver circuit.
B160212›
DTC B160212 indicates the SRS (Supplemental Restraint System) control unit detects an abnormal short circuit between the driver’s front airbag inflator circuit and the vehicle power supply (12V+B). The inflator circuit normally maintains a high-resistance state (typically 2-3Ω, determined by the inflator internal resistance). The control unit continuously monitors circuit voltage and resistance via an internal bridge detection circuit. A short circuit to power indicates the voltage at one or both ends of the circuit continuously exceeds the threshold (typically above 5V) and the resistance is abnormally low. This fault triggers the safety protection mechanism. The system immediately enters fail-safe mode and disables the airbag deployment function to prevent accidental deployment caused by short-circuit current. Hardware faults such as an internal clock spring short circuit, damaged wiring harness insulation contacting a power wire, or a driver transistor breakdown inside the SRS ECU may accompany this fault.
B160A-00›
This DTC indicates the Airbag Control Unit (ACU) detects the Driver Airbag (DAB) firing circuit resistance is below the calibrated threshold (close to 0 Ω), indicating a short circuit. In the BYD SRS system, normal airbag circuit resistance ranges from 1.5 to 3.0 Ω. A resistance of 0 Ω typically indicates a short between the positive and negative terminals in the airbag wiring harness, clock spring, or connector. An internal driver circuit breakdown within the ACU can also cause this issue. This fault triggers the safety system fail-safe mode, illuminates the instrument panel SRS warning light, and may prevent airbag deployment during a collision. This severely compromises passive safety and requires immediate repair.
B160A›
DTC B160A indicates the driver front airbag (DAB) ignition circuit resistance is 0 ohms, representing a short circuit. Normally, the airbag squib has a standard resistance of 2-5 ohms. When the SRS ECU detects circuit resistance near 0 Ω, it identifies a short to ground, short to power, or internal short in the airbag module. This safety-critical fault prevents normal airbag deployment during a collision or causes accidental deployment. A 0-ohm resistance typically indicates an internal ribbon cable short in the clock spring (spiral cable), damaged harness insulation shorting to ground, or an internal igniter short within the airbag module.
B160A1A›
DTC B160A1A indicates abnormally high resistance (open circuit or high-resistance condition) in the driver-side front airbag (stage 1) ignition circuit. This is a critical Supplemental Restraint System (SRS) safety fault. Normal airbag igniter resistance is 1.5-3.5Ω. If the system detects resistance continuously exceeding the threshold (typically >5Ω or open circuit), it identifies an ignition circuit integrity fault. The SRS control unit then illuminates the instrument cluster airbag warning light and enters fail-safe mode. This condition may prevent the driver-side airbag from deploying during a collision. The fault indicates an electrical connection issue in the circuit, not an explosion risk from the airbag itself.
B160B-00›
DTC B160B-00 indicates the SRS (Supplemental Restraint System) ECU detects the driver's front airbag (steering wheel airbag) igniter circuit resistance is below the calibrated threshold (usually <1.0Ω). Normal airbag igniter resistance is 2.0-3.0Ω. Low resistance usually indicates a circuit short to ground, an internal short in the airbag module, or abnormal connector continuity. This fault causes the SRS ECU to register an abnormal airbag circuit. The airbag may fail to deploy during a collision or deploy unintentionally while driving. Consequently, the system illuminates the airbag warning lamp and disables the airbag function.
B160B›
DTC B160B indicates the SRS (Supplemental Restraint System) control unit detects the driver frontal airbag (DAB) igniter (squib) circuit resistance is below the calibrated threshold (typically <1.5Ω; standard range is 2.0±0.3Ω). This active fault indicates an abnormally low-resistance path in the circuit. A partial short circuit, an internal turn-to-turn short in the igniter, or a wiring harness short to ground can cause this condition. The low resistance abnormally increases the airbag circuit current, creating a risk of unintended airbag deployment. Alternatively, during a collision, the excessive current may trigger the ACU protective cutoff and prevent normal deployment. When this DTC triggers, the SRS system typically enters fail-safe mode and disables the driver-side airbag.
B160B1A›
DTC B160B1A indicates the Driver Airbag (DAB) deployment circuit resistance falls below the normal threshold set by the SRS ECU (typically 2.0-3.0Ω; values below 1.0Ω trigger this fault). This constitutes a Supplemental Restraint System (SRS) hard-wire fault. The ECU detects an abnormally low-resistance path in the deployment circuit. Potential causes include a wiring short to ground, an internal short in the clock spring, an internal short in the airbag module, or a short between connectors. This fault forces the airbag system into fail-safe mode and continuously illuminates the instrument cluster airbag warning light. In extreme cases, the airbag may fail to deploy during a collision because the ECU misinterprets the condition as a short circuit and disables the deployment circuit. In very rare cases, wiring interference creates a risk of unintended deployment.
B160C›
DTC B160C indicates the SRS (Supplemental Restraint System) control unit detects the driver-side front airbag (steering wheel main airbag) ignition circuit resistance exceeds the normal upper limit (normal range: 2.0–3.0 Ω; fault threshold: ≥4.0 Ω or open circuit). This hard or intermittent fault indicates a high-resistance condition in the airbag ignition circuit. Poor contact, loose wiring connections, or component aging can cause this condition. Excessive resistance reduces circuit current. During a collision, the ACU (Airbag Control Unit) may fail to generate sufficient ignition current to trigger the gas generator, causing airbag deployment failure and severely compromising occupant protection. This DTC illuminates the SRS warning lamp, forces the system into a degraded protection mode, and disables airbag deployment for this circuit.
B160C1B›
This fault code indicates the driver front airbag (DAB) igniter (gas generator) resistance exceeds the normal threshold range set by the SRS control module (typically 2.0–3.0 Ω, depending on the vehicle model). "High resistance" usually indicates a high-impedance point in the circuit. Causes include poor wiring connections, oxidized connectors, poor internal contact in the clock spring (spiral cable), or an aging airbag igniter. This active safety system fault causes the SRS control module to classify the driver airbag as unreliable. This condition may prevent airbag deployment during a collision, or in some cases, continuously illuminate the warning light and store a fault code, severely compromising passive safety protection.
B1610-00›
DTC B1610-00 indicates the SRS (Supplemental Restraint System) ECU detected abnormal resistance in the front passenger-side frontal airbag ignition circuit, specifically 0 Ω (short circuit) or infinite resistance (open circuit). In the BYD fault definition system, this code means "front passenger frontal airbag disconnected," indicating a loss of circuit integrity between the SRS ECU and the front passenger airbag module. This hard fault triggers the system fail-safe mode: the SRS ECU disables all airbag deployment (including the driver-side, side, and curtain airbags) and continuously illuminates the instrument cluster airbag warning lamp. Because this fault involves the occupant passive safety system, it carries the highest priority. The airbag system returns to normal standby status only after fault repair.
B1610›
DTC B1610 indicates the Airbag Control Unit (ACU) detects an open circuit in the front passenger airbag squib circuit. Resistance falls outside the normal range (normal: approximately 1.5-3.0Ω; fault: typically >10Ω or infinite). This indicates a physical break in the circuit between the ACU and the front passenger airbag module (located inside the right side of the dashboard). Possible causes include a loose wiring harness connector, an open circuit in the airbag module inflator, wiring harness wear or breakage, or a clock spring fault (if applicable). This fault prevents the front passenger airbag from deploying during a collision, severely compromising occupant protection. Other vehicle systems continue to operate normally.
B16101B›
B16101B is an ISO 15031-6 standard diagnostic trouble code (DTC). 'B' represents the Body system, '16' specifies the airbag system (SRS), '10' refers to the Passenger Frontal Airbag circuit, and '1B' is the sub-fault code indicating circuit resistance exceeds the threshold (open circuit or high resistance). This fault indicates the SRS ECU (airbag control unit) cannot establish effective communication with the Passenger Frontal Airbag module and cannot detect normal squib resistance (standard value: 2.0-3.0Ω). The ECU triggers this fault code when it detects infinite circuit resistance (open circuit) or resistance exceeding 6.0Ω. The airbag system enters fail-safe mode. The passenger frontal airbag will not deploy in a collision, and the instrument panel SRS warning light illuminates continuously, indicating a functional defect in the occupant restraint system.
B1611›
DTC B1611 indicates a short to ground in the front passenger airbag (PAB) ignition circuit. Specifically, the SRS control unit detects an abnormally low-resistance connection (typically less than 2-3Ω) between the passenger airbag inflator circuit (usually the high-level trigger wire) and vehicle ground (GND). This short circuit prevents normal airbag deployment (diverting ignition energy to ground) or, in extreme cases, causes inadvertent deployment due to static electricity or electromagnetic interference. This fault constitutes a severe active safety system failure. The SRS control unit immediately disables the front passenger airbag, illuminates the airbag warning light, and may simultaneously lock the seat belt pretensioner, severely compromising passive safety performance.
B161111›
DTC B161111 indicates a short to ground in the front passenger airbag (PAB) ignition circuit. In the BYD SRS (airbag) system architecture, this DTC sets when the airbag control unit (ACU) detects the resistance between the front passenger airbag ignition wiring and body ground falls below the calibrated threshold (usually < 2Ω). This constitutes a hard fault in the active safety system, indicating compromised airbag circuit integrity. Potential risks include: 1) the front passenger airbag fails to deploy during a collision, resulting in a loss of occupant protection; 2) abnormal wiring causes unintended airbag deployment in extreme cases. This latch-type fault (Latch DTC) requires a VDS or dedicated diagnostic tool to clear. It continuously illuminates the instrument cluster SRS warning lamp (solid, not flashing).
B1612-00›
DTC B1612-00 indicates the airbag control module (SRS ECU) detected an unintended electrical connection between the front passenger frontal airbag inflator circuit and the vehicle positive power supply (B+), constituting a short to power. In the airbag system dual-stage ignition architecture, the ECU monitors the inflator circuit voltage state through internal diagnostic resistors. Normally, the circuit maintains high impedance to the power supply (open-circuit state). The ECU logs a short to power when it detects circuit voltage abnormally close to battery voltage (typically >5V or a sustained high level) instead of the expected low-voltage state. This is a hardwire circuit fault. Potential risks include: 1) the airbag fails to deploy in a collision because supply voltage clamps the ignition circuit, preventing sufficient firing current; 2) unintended airbag deployment in extreme cases if the safety capacitor design interacts with the short to power. Possible fault locations include the clock spring (spiral cable), instrument panel wiring harness, airbag module connector, or the internal SRS ECU driver circuit. On some BYD models, this DTC logic also monitors the front passenger seat Occupant Classification System (OCS) power supply circuit for abnormalities. Because the OCS sensor status directly determines whether the system permits front passenger airbag deployment, a short to power in the OCS signal circuit triggers the same DTC.
B1612›
DTC B1612 indicates the SRS (Supplemental Restraint System) detected an abnormally low-resistance connection between the front passenger frontal airbag igniter circuit and the vehicle power supply (B+), indicating a short to power. Under normal conditions, the airbag igniter circuit remains in a high-resistance state isolated from both power and ground (typically greater than 10kΩ). The SRS ECU momentarily connects power through an internal switch only during airbag deployment. A short to power means one or both sides of the igniter continuously connect to the 12V power supply. This condition causes: (1) failure of the airbag to deploy during a collision (the ECU detects the circuit fault and inhibits triggering); (2) unintended airbag deployment in extreme cases due to abnormal current; (3) damage to the diagnostic driver circuit inside the SRS ECU. This fault involves the connections between the front passenger airbag module, clock spring (spiral cable), floor wiring harness, and SRS ECU.
B161212›
DTC B161212 indicates a short to battery in the passenger front airbag deployment circuit. In the SRS (Supplemental Restraint System) circuit, two wires (typically high-side and low-side deployment wires) connect the airbag module to the Airbag Control Unit (ACU). Under normal conditions, these two wires have no continuity to the vehicle power supply (+12V/B+). When the diagnostic system detects abnormally low resistance (typically <10Ω) between the airbag circuit wiring and the battery positive terminal, it identifies a short to battery. This fault forces the Airbag Control Unit into fail-safe mode, disabling the passenger airbag to prevent accidental deployment and personal injury. Damaged wiring harness insulation, an internal connector short, or an internal airbag module fault can cause this condition. Address this Level 1 safety fault immediately.
B161A›
DTC B161A indicates the Airbag Control Unit (ACU) detects abnormally low resistance, approaching 0 Ω (typically <1.0 Ω), in the front passenger frontal airbag ignition circuit. Normal airbag igniter resistance remains between 2.0-3.0 Ω. A resistance of 0 Ω usually indicates a short to ground, a wire-to-wire short, or an internal short in the airbag module igniter. This fault causes the SRS system to enter fail-safe mode: 1) The airbag may fail to deploy during a collision due to the short circuit, causing a loss of passive protection; 2) Short-circuit current may cause unintended airbag deployment in extreme cases; 3) The system illuminates the instrument cluster airbag warning light and may store related freeze frame data. This is a hard fault (continuous) requiring immediate repair for occupant safety.
B161A1A›
DTC B161A1A indicates the Supplemental Restraint System (SRS) detects the front passenger airbag (PAB) ignition circuit resistance is 0 ohms or below the threshold (usually <0.8Ω). The SRS ECU monitors circuit integrity using a constant current source to measure the squib circuit resistance. Normal resistance is 1.5-3.5Ω (typical value 2.0-2.8Ω). A resistance of 0 indicates a short circuit. Possible causes include an internal short in the airbag module squib, an internal short in the clock spring, a wiring harness short to ground or power, or a faulty internal sampling circuit in the SRS ECU. This fault prevents the front passenger airbag from deploying during a collision (fail-safe mode) or causes unintentional deployment (extremely rare but dangerous). The system illuminates the airbag warning light and disables the front passenger airbag.
B161B-00›
DTC B161B-00 indicates the airbag control unit (SRS ECU) detects the front passenger airbag (PAB) igniter circuit resistance is below the calibrated threshold (typically below 1.5-2.0Ω, depending on the vehicle software version). The standard SRS airbag igniter resistance is generally 2.0±0.5Ω. Low resistance typically indicates a short circuit. Potential causes include an internal short in the airbag igniter, a wiring harness short to ground, a short between connector terminals, or an internal short in the clock spring. This fault forces the SRS system into a degraded mode. The system may disable the front passenger airbag (preventing deployment) or, in extreme cases, risk unintended deployment. When this DTC triggers, the instrument panel airbag warning light remains illuminated and the system halts collision detection for the front passenger airbag.
B161B›
DTC B161B indicates the Airbag Control Module (ACM) detects the Passenger Airbag (PAB) igniter (inflator) resistance is below the system-calibrated lower threshold (typically below 1.0–1.5 Ω; normal range is 1.5–3.5 Ω). This fault represents an abnormal electrical characteristic in the SRS circuit or components. Potential causes include an internal short circuit in the igniter, a wiring harness short to ground, a short between connector pins, or a faulty internal detection circuit within the control module. Upon detecting this fault, the system enters fail-safe mode and illuminates the airbag warning lamp. This condition compromises occupant safety; during a collision, the passenger airbag may fail to deploy (fail-safe) or, in rare cases, deploy unexpectedly due to false triggering.
B161B1A›
DTC B161B1A indicates the airbag control module (SRS ECU) detects the Passenger Front Airbag ignition circuit resistance is below the calibrated threshold (typically below 1.0-1.5Ω; normal range is generally 2.0-5.0Ω). Low resistance typically indicates a parallel short circuit path in the airbag circuit. Potential causes include a wiring harness short to ground, bridged connector pins, or an internal short circuit in the airbag inflator. The ECU classifies this as a "Low Resistance" fault. This condition can prevent proper airbag deployment during a collision because the short circuit diverts the current. In extreme cases, static electricity or electromagnetic interference can cause unintended deployment. Consequently, the SRS system enters fail-safe mode, illuminates the airbag warning light, and disables the passenger front airbag.
B161C-00›
DTC B161C-00 indicates the Supplemental Restraint System (SRS) control unit detected the front passenger airbag (PAB) ignition circuit resistance exceeds the normal upper limit. In BYD SRS systems, the control unit continuously monitors each airbag squib resistance via a low-current detection circuit. The normal range is typically 2.0-3.0Ω. If the resistance exceeds approximately 6.0Ω (high-resistance threshold), the control unit logs a 'high resistance' fault. During a collision, this fault may prevent or delay front passenger airbag deployment, severely compromising occupant passive safety. High resistance in the ignition circuit causes this fault. Potential root causes include poor contact, oxidized wiring, loose connectors, or an aging squib inside the airbag module.
B161C›
DTC B161C indicates the SRS (Supplemental Restraint System) ECU detects the front passenger frontal airbag ignition circuit resistance exceeds the calibrated upper limit (typically >5Ω). Normal airbag igniter resistance is between 2.0Ω and 3.0Ω. Excessive resistance indicates high resistance or an open circuit risk in the ignition circuit. This prevents the ECU from supplying sufficient ignition current (typically 1.2A or higher) during a collision, causing the front passenger airbag to fail to deploy and severely compromising passive safety. This is a hard fault. The system illuminates the airbag warning lamp and disables the front passenger airbag. Inspect and repair immediately.
B161C1B›
DTC B161C1B indicates the Passenger Front Airbag ignition circuit resistance exceeds the threshold set by the SRS control module (normal range is typically 2.0-3.0Ω; the module triggers the code upon detecting resistance >3.5Ω or an open circuit). This active SRS system fault means the passenger front airbag may fail to deploy during a collision, or abnormal signals may force the system into fail-safe mode. In the BYD diagnostic protocol, the '1B' suffix specifically denotes 'resistance too high/open circuit'. Poor wiring connections, oxidized connectors, poor clock spring contact, or increased internal airbag module resistance typically cause this condition. This fault illuminates the instrument panel SRS warning lamp and disables the passenger front airbag. As a safety-critical fault, it requires immediate repair.
B1620-00›
DTC B1620-00 indicates the airbag control unit (SRS ECU) detects an open circuit or disconnected electrical connection at the left front seat side airbag (Driver Side Airbag). Specifically, this fault indicates a circuit interruption between the seat-integrated side airbag module (typically located on the side of the seat backrest) and the vehicle wiring harness. The SRS ECU continuously monitors the airbag igniter circuit resistance (standard value: 2.0-3.0Ω) via a low-level signal line. The ECU sets this DTC when the resistance exceeds the threshold (typically >6Ω or open circuit) for longer than the specified time (typically >2 seconds). This is a hard fault that prevents the left front seat side airbag from deploying during a collision. The system also illuminates the instrument cluster SRS warning lamp and may disable the entire airbag system deployment function, severely compromising passive safety.
B1620›
DTC B1620 indicates the left Body Domain Controller detects an abnormal condition in the driver's side (left front) door lock. Specifically, the controller detects an implausible door lock position sensor signal, an open or short circuit in the door lock drive circuit, or a missing door lock status feedback signal. Typical causes include faults in the door lock assembly microswitch, position sensor, actuator motor, or associated wiring harness connections. This fault causes abnormal door status displays, remote locking failures, false anti-theft alarms, and false 'door open' warnings while driving, compromising vehicle security and driving safety.
B16201B›
B16201B is a BYD SRS (Supplemental Restraint System) diagnostic code indicating a communication interruption or open electrical connection between the driver's seat side airbag and the SRS control unit. This DTC sets when the SRS ECU detects the driver's side airbag circuit resistance exceeds the standard range (typically 2.0-3.0Ω ±0.5Ω), indicating an open circuit or high resistance. This incomplete airbag deployment circuit prevents the system from igniting the gas generator during a side impact. This fault forces the SRS into a degraded mode. The driver's seat side airbag becomes inoperative, but other airbags (front, curtain) typically remain functional. Despite involving the high-voltage interlock and safety systems, the vehicle remains drivable with reduced occupant protection. This fault continuously illuminates the instrument cluster airbag warning light on some models.
B1621-00›
DTC B1621-00 indicates a short to ground in the driver side airbag (typically the seat-mounted side airbag or side curtain airbag) igniter circuit. In the BYD SRS system, the ECU continuously monitors the circuit resistance of each airbag igniter (normal value: approximately 2.0-5.0 Ω). When the ECU detects resistance below 1.0 Ω or voltage close to 0 V, it identifies a short to ground. This fault causes the system to disable the affected airbag circuit, preventing normal deployment during a side impact. In extreme cases, unstable resistance at the short circuit causes intermittent contact, posing a risk of unintended airbag deployment. When this DTC triggers, the SRS control unit illuminates the instrument cluster airbag warning light and stores freeze frame data recording the vehicle status at the time of the fault.
B1621›
DTC B1621 indicates the SRS (Supplemental Restraint System) electronic control unit detects an abnormally low-resistance path (typically <0.5Ω) between the driver side airbag squib circuit and body ground (GND). Under normal conditions, airbag squib resistance must measure 2.0-3.0Ω, and insulation resistance to ground must exceed 1MΩ. A short to ground indicates an unintended ground connection in the squib circuit. This causes: 1) During a collision, the ground connection bypasses current, preventing proper airbag deployment and resulting in a loss of side-impact protection; 2) In extreme cases, wiring vibration may cause the ECU to misinterpret the short as a valid deployment signal, creating a risk of unintended airbag deployment; 3) The SRS system enters fail-safe mode, illuminates the instrument cluster airbag warning light, and disables the associated airbag function. This fault affects a core active safety system component and requires immediate repair.
B162111›
DTC B162111 is a BYD SRS (Supplemental Restraint System) diagnostic code indicating a short to ground in the driver-side side airbag ignition circuit. In BYD electrical architecture, this fault indicates the airbag control unit (ACU) detects abnormally low igniter circuit resistance (close to 0Ω) in the driver seat side airbag (typically integrated into the seat backrest or B-pillar), falling below the calibrated threshold (typically < 1.0Ω). This signifies an unintended connection between the positive or negative wire in the ignition circuit and the vehicle chassis (GND). This fault causes the ACU to flag the airbag as unsafe, immediately illuminate the instrument cluster SRS warning lamp, and disable deployment of the affected side airbag. In a collision, this airbag fails to inflate, severely compromising occupant side-impact protection. Additionally, the short circuit can trigger overcurrent protection in the internal ACU driver chip and, in extreme cases, risk unintended deployment, forcing the system into fail-safe mode.
B1622-00›
DTC B1622-00 indicates the driver side airbag squib circuit is shorted to the vehicle constant power supply (+B, battery voltage). The SRS (Supplemental Restraint System) ECU continuously monitors the airbag igniter circuit resistance and voltage. When detecting an abnormally high voltage on the igniter wiring (approaching the 12V supply voltage), the ECU registers a short to power. This fault is extremely dangerous and may cause: 1) accidental airbag deployment while driving, resulting in serious personal injury; 2) failure of the airbag to deploy during a collision due to the circuit fault; 3) the SRS entering fail-safe mode, disabling all airbag functions. This is a hard fault (Hard DTC). Once confirmed, the system triggers a severe warning and prohibits further vehicle operation.
B1622›
DTC B1622 indicates the Supplemental Restraint System (SRS) control module detects an abnormally low-resistance connection (typically below 1.0Ω) between the driver side airbag inflator circuit and battery positive (B+, 12V). Normally, the airbag inflator circuit maintains a high-resistance state (open circuit or the 2-3Ω resistance of the inflator itself). A short to power means the SRS module detects supply voltage instead of the expected high-resistance signal when checking circuit integrity. This fault poses extreme safety risks. During a collision, the SRS module may fail to trigger the inflator circuit, preventing airbag deployment. Additionally, specific operating conditions (such as intermittent wiring contact or voltage fluctuations) can cause unintended airbag deployment, severely threatening driver safety.
B162212›
DTC B162212 indicates abnormal continuity between the squib circuit of the driver side airbag (usually the seat-mounted side airbag) and the vehicle positive power supply (B+, battery voltage). In the SRS (Supplemental Restraint System) control logic, the airbag squib circuit must maintain a high-impedance open state at rest. The control unit determines circuit integrity by monitoring circuit voltage. Detecting a short to power in this circuit indicates damaged wiring insulation contacting a constant power wire, or an insulation failure of the igniter coil inside the airbag module. This fault immediately forces the SRS into fail-safe mode, which: 1) Disables the driver side airbag, preventing deployment during a side impact; 2) Illuminates the airbag warning lamp; 3) Creates a risk of unintended airbag deployment in extreme cases (despite multiple protections in modern systems). Because it involves a core component of the passive safety system, this fault classifies as severe and requires immediate repair.
B162A-00›
DTC B162A-00 indicates an abnormal left front seat side airbag ignition circuit resistance of 0 ohms, representing a short-to-ground fault. Normal airbag inflator resistance is 2.0-3.0 Ω. A 0 Ω reading means the ignition circuit shorts to the vehicle body ground. Potential causes include an internal airbag module short circuit, damaged wiring harness insulation shorting to ground, or shorted connector terminals. This fault causes the SRS system to detect a risk of accidental ignition or deployment failure. Consequently, the SRS system disables the airbag's collision protection function and illuminates the airbag warning light on the instrument cluster.
B162A›
DTC B162A indicates the airbag control module (SRS ECU) detects a driver airbag ignition circuit resistance of 0 Ω or below the 1.5 Ω threshold, identifying a short to ground or a shorted circuit. In the BYD SRS system, this circuit includes the clock spring, spiral cable, connectors, and airbag inflator. A 0 Ω resistance means current may flow directly to ground. The ECU disables the airbag to prevent accidental deployment and illuminates the instrument cluster airbag warning lamp. This fault constitutes a hard short circuit, unlike an open circuit (infinite resistance). However, broken wires inside the clock spring contacting each other or grounding can also cause an intermittent short circuit. This fault prevents the driver front airbag from deploying during a collision, severely compromising passive safety.
B162B1A›
This DTC indicates the driver side airbag squib resistance falls below the SRS control unit threshold (typically <1.6Ω). Normal airbag squib resistance ranges from 1.6Ω to 2.4Ω. Low resistance indicates an abnormal short-circuit path in the circuit. Potential causes include an internal airbag squib short circuit, a wiring harness short to ground, or a grounded connector terminal. The SRS system classifies this fault as an unintended deployment risk, automatically disconnects the airbag circuit, and illuminates the airbag warning lamp. During a side impact, the airbag may fail to deploy, disabling driver side protection. Additionally, the BYD SRS fail-safe mechanism may trigger the seat belt pretensioner linked protection logic, compromising overall passive safety system performance.
B162A1A›
DTC B162A1A indicates the airbag control module (SRS ECU) detects a resistance of 0 ohms, or close to 0, in the driver's side airbag circuit (usually integrated into the seat side). Normal airbag circuit resistance ranges from 2-3 ohms (including the airbag inflator resistance and wiring harness impedance). A resistance of 0 indicates a short circuit. Possible causes include damaged wiring harness insulation causing a short between positive and negative terminals, connector pins shorting to ground, an internal short in the airbag inflator, or an SRS control module sampling circuit fault. This fault prevents the side airbag from deploying during a collision, resulting in a loss of protection. In extreme cases, poor contact at the short circuit point can produce arcing and risk unintended deployment. Triggering this fault code illuminates the instrument cluster airbag warning light and may disable the entire airbag system.
B162B-00›
DTC B162B-00 indicates the airbag control unit (SRS ECU) detects the driver side airbag (located on the side of the driver seat) igniter circuit resistance is below the system threshold (normal range: 2.0-5.0Ω; low resistance indicates a value below the lower limit or a near short circuit). Electrically, this indicates an abnormally low-resistance path in the circuit. Potential causes include a wiring short to ground, an internal short circuit in the airbag module, or abnormal connector conduction. This fault causes the SRS system to classify the driver side airbag as unsafe. During a collision, excessive current may prevent the igniter from deploying the airbag. Additionally, a risk of accidental deployment (non-collision deployment) exists. Consequently, the system illuminates the instrument cluster airbag warning light and may disable the entire airbag system, severely compromising occupant side-impact protection.
B162B›
DTC B162B indicates the SRS (Supplemental Restraint System) control module detects the driver-side side airbag (typically the seat side airbag or side curtain airbag) igniter (squib) resistance is below the system threshold (typically <1.0Ω or below the standard range of 2.0-3.0Ω). This fault indicates a short-circuit risk in the wiring or airbag assembly. The system enters safety mode to prevent accidental airbag deployment or failure. Triggering this fault disables the affected airbag circuit. The airbag may fail to deploy during a side-impact collision, severely compromising occupant protection. Additionally, a continuously illuminated SRS warning light indicates the entire airbag system may operate in a degraded protection mode.
B162C-00›
DTC B162C-00 indicates the SRS (Supplemental Restraint System) control unit detects resistance exceeding the calibrated threshold in the driver side airbag ignition circuit. The driver side airbag typically mounts in the side of the driver seat backrest or inside the door trim panel. Normal circuit resistance ranges from 2-3 ohms; the fault threshold typically exceeds 3.5-4 ohms. The SRS ECU monitors circuit integrity by sending a low-current signal through its internal detection circuit to the airbag igniter. High-resistance connections (e.g., poor contact, loose harness connections, oxidation, or partial wire breaks) increase total circuit resistance, causing the ECU to register a high-resistance fault. This fault severely compromises side-impact protection. Excessive resistance limits current, potentially causing the driver side airbag to deploy late or fail to deploy during a collision. The system illuminates the SRS warning lamp and may disable the entire airbag system, resulting in a complete loss of collision protection.
B162C›
DTC B162C indicates the driver side airbag ignition circuit resistance exceeds the normal upper limit set by the SRS control unit (typically >3.5Ω; normal value 1.5-3.0Ω). The SRS ECU continuously monitors the airbag inflator (gas generator) circuit resistance via its internal detection circuit. Excessive resistance indicates poor contact, a partial open circuit, or inflator aging within the ignition circuit. This condition may prevent the circuit current from reaching the ignition threshold (typically 1.5-2.0A required) during a collision. This fault prevents the side airbag from deploying normally in a crash. Repair this safety-critical fault immediately.
B1630-00›
DTC B1630-00 indicates the SRS (Supplemental Restraint System) control module detects an open circuit or high resistance in the right front seat side airbag module circuit. The resistance exceeds the calibrated range (typically >10Ω). This represents a hard fault in the airbag system; the right front seat side airbag fails to deploy during a side-impact collision. The system enters fail-safe mode and continuously illuminates the instrument cluster airbag warning light. Potential causes include an open wiring circuit, a disconnected connector, an open airbag squib, or excessive contact resistance.
B162C1B›
DTC B162C1B is a BYD BMS (Battery Management System) fault code. It indicates abnormal communication between a specific Battery Information Collector (BIC) inside the battery pack and the main BMS, or excessive resistance in the sampling circuit. Specifically, "B16" designates the BMS subsystem, "2C" identifies a communication or sampling fault in a specific BIC module, and "1B" is the subtype code indicating excessive resistance, an open circuit, or poor contact in that BIC module's CAN communication circuit. This failure prevents the system from uploading voltage and temperature data for that battery cell group, affecting battery balancing management, SOC calculation, and the high-voltage interlock function. In severe cases, the fault may prevent the vehicle from enabling the high-voltage system or cause a loss of drive power while driving.
B174B1A›
This DTC indicates the left rear side airbag squib resistance falls below the normal threshold set by the SRS control module (ACU) (typically below 1.2Ω-1.5Ω; standard range is generally 1.5Ω-3.5Ω). Low resistance usually indicates a short circuit in the squib circuit. Possible causes include a wiring harness short to ground, a wire-to-wire short, an internal connector short, or an internal short within the airbag module itself. This fault causes the SRS system to classify the airbag as unsafe. The airbag may fail to deploy during a collision (as the system may disable the circuit to prevent accidental deployment), or it poses a risk of unintended deployment. This is an active safety system fault requiring immediate repair.
B1630›
DTC B1630 indicates the SRS (Supplemental Restraint System) detected an open circuit or abnormally high resistance in the front passenger seat side airbag circuit. The ECU determines the airbag module is incorrectly connected. Potential fault locations include the front passenger seat side airbag assembly, connecting wiring, under-seat wiring harness connector, or the airbag control unit (ACU) internal driver circuit. During system self-check, the ACU confirms the connection status by monitoring the airbag squib circuit resistance. Normal resistance typically ranges from 2.0-3.0 ohms (depending on the vehicle model). If the ACU detects an open circuit (infinite resistance) or resistance exceeding the threshold, it triggers this fault code. This fault prevents the front passenger side airbag from deploying during a side-impact collision. The system also illuminates the instrument cluster airbag warning light and may disable the entire SRS, significantly reducing vehicle passive safety. Note: Some vehicle models or documentation define B1630 as a seat belt pretensioner circuit fault. Consult the specific vehicle service manual during repair.
B16301B›
This fault code indicates the Airbag Control Unit (ACU) detects an open circuit or high resistance in the communication circuit between the front passenger side airbag (usually installed on the outboard side of the front passenger seat or inside the B-pillar trim panel) and the ACU. Specifically, the ACU cannot detect the standard 2-3 ohm resistance value in this airbag circuit and determines a 'disconnected' state. This prevents the side airbag from deploying normally during a side impact, severely reducing side impact protection for the front passenger. The system simultaneously illuminates the SRS fault warning light on the instrument cluster and may trigger the system safety protection mechanism, disabling the entire airbag system to prevent accidental deployment.
B1631-00›
DTC B1631-00 indicates the airbag control unit (SRS ECU) detected a short to ground in the front passenger (right front) seat side airbag inflator circuit. The SRS ECU verifies circuit integrity by monitoring the airbag inflator circuit resistance. Normally, this circuit exhibits high resistance (open circuit or a specific resistance range, typically >1MΩ insulation to ground). If the ECU detects an abnormal resistance drop between the inflator circuit and body ground (below the threshold, typically <1Ω), it registers a short to ground. This fault triggers the safety protection mechanism. The ECU disables the airbag to prevent accidental deployment, illuminates the instrument cluster SRS warning light, stores the DTC, and may sound a warning buzzer. Because the side airbag is critical for side impact protection, this fault disables front passenger side impact protection and constitutes a severe safety fault.
B1631›
DTC B1631 indicates a short to ground in the front passenger side airbag ignition circuit. In the BYD SRS (Supplemental Restraint System), this fault code indicates the airbag control unit (ACU) detects an abnormally low resistance (typically <1Ω) between the front passenger side airbag (usually installed in the seat side or door trim panel) ignition wiring and body ground. Normal airbag circuit resistance should measure between 2.0 and 3.0Ω. This fault means: 1) the airbag may fail to deploy during a collision, resulting in a loss of side impact protection; 2) extreme cases pose a risk of unintended deployment; 3) the SRS system enters fail-safe mode, illuminating the instrument panel airbag warning light and potentially disabling other airbag functions. This hard short circuit requires immediate repair to ensure occupant safety.
B163111›
DTC B163111 indicates the SRS (Supplemental Restraint System) control module detects an abnormally low-resistance path to body ground (short to ground) in the front passenger side airbag squib circuit (typically the seat side airbag or curtain airbag). Under normal operating conditions, the airbag squib circuit resistance must remain around 2-3 Ω, and the insulation resistance to ground must exceed 1 MΩ. The control module logs a short to ground when it detects circuit resistance approaching 0 Ω or current leaking to ground. This fault prevents the side airbag from deploying during a side-impact collision, eliminating side-impact protection for the occupant. The circuit abnormality also creates a potential risk of unintended deployment, although a short to ground typically causes a non-deployment failure rather than accidental triggering. This fault constitutes a severe active safety system failure. Remove the vehicle from service immediately until repaired.
B1632›
DTC B1632 indicates the SRS (Supplemental Restraint System) ECU detected a short to power (B+) in the front passenger side airbag igniter circuit (typically the right seat airbag or side curtain airbag). Normally, the airbag igniter circuit maintains a low voltage (near 0V). The ECU supplies high current only when triggering airbag deployment. If the ECU continuously detects circuit voltage near battery voltage (12V), it identifies a short to power. This fault forces the SRS into fail-safe mode, disables front passenger side airbag deployment, and illuminates the airbag warning light. Potential causes include damaged wiring insulation, shorted connector terminals, an internal short in the airbag module, or a faulty internal ECU driver circuit.
B1632-00›
B1632-00 indicates a short circuit to vehicle power (B+) in the front passenger (right) side airbag ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, this fault specifically refers to abnormal continuity between the inflator circuit of the front passenger seat side airbag or the right curtain airbag and 12V constant power or ignition power. This fault is a hard short. The SRS control unit (ACU) detects the ignition circuit voltage continuously exceeding the threshold (typically >5V). To prevent unexpected deployment, the system immediately cuts off the affected airbag ignition circuit and illuminates the airbag fault warning lamp (SRS MIL). This fault presents an extremely high safety risk: the short circuit may cause unexpected airbag deployment resulting in personal injury. Additionally, the fault prevents normal airbag deployment, disabling collision protection.
B163212›
DTC B163212 indicates a short to battery positive (B+) in the front passenger seat side airbag ignition circuit. Technically, this means an abnormal connection to the permanent 12V supply exists in the wiring harness or connectors between the airbag control module (SRS ECU) and the front passenger seat side airbag. Normally, the airbag igniter terminals maintain a high resistance (>10kΩ) in the non-deployed state or only receive a low-current monitoring signal from the ECU. A short to power causes the following: 1) The SRS system enters protection mode, cutting power to this circuit to prevent unintended deployment; 2) The front passenger seat side airbag completely fails, preventing deployment during a side impact; 3) A potential unintended deployment risk arises. Although the ECU typically features short-circuit protection, a continuous short to power can overheat and damage the control module's internal driver chip. ISO 26262 classifies this fault as a high Automotive Safety Integrity Level (ASIL D) fault, requiring immediate resolution.
B163A-00›
DTC B163A-00 indicates the SRS (Supplemental Restraint System) ECU detects 0Ω resistance in the right front seat side airbag circuit, technically defined as a short circuit. Normal airbag inflator resistance ranges from 1.5-3.5Ω (typically 2.0±0.5Ω). A 0Ω reading indicates a short to ground, a short to power, or an internal short within the airbag assembly. This fault prevents the side airbag from deploying during a collision or, in extreme cases, causes accidental deployment due to wiring interference. The seat houses the side airbag and undergoes frequent fore-aft and angle adjustments. This movement subjects the wiring harness between the seat and floor to long-term bending, making it a common failure point.
B163A›
This fault code indicates the Supplemental Restraint System (SRS) detects a 0Ω resistance in the front passenger side airbag firing circuit (typically located in the seat side or B-pillar/curtain). Normal airbag igniter resistance is 1.6-2.4Ω. A 0Ω resistance indicates a low-impedance short circuit. Possible causes include a wiring harness short to ground, shorted connector pins, an internal short in the airbag inflator (igniter), or a faulty internal monitoring circuit in the SRS control unit (ACU). The ECU disables this airbag circuit to prevent accidental deployment. The airbag will fail to deploy during a side impact, severely compromising occupant protection. Some early repair data or specific vehicle models define B163A as an anti-theft system communication fault. Always reference the current vehicle repair manual for actual diagnosis.
B163A1A›
This fault code indicates the front passenger side airbag igniter circuit resistance measures 0 ohms, indicating a Short to Ground fault. Normal airbag igniter resistance in the SRS (Supplemental Restraint System) is typically 1.5-3.0 Ω. A 0 ohm reading indicates a direct ground path in the circuit. Damaged wiring harness insulation contacting ground, shorted connector terminals, or an internal short circuit in the airbag module igniter can cause this condition. This fault triggers the SRS control unit fail-safe mode, illuminates the airbag warning light, and can prevent the passenger side airbag from deploying during a collision, severely compromising occupant side impact protection. BYD E2/E3 and similar models use seat-integrated side airbags; frequent seat adjustment easily causes wiring harness fatigue damage.
B163B-00›
DTC B163B-00 indicates the SRS (Supplemental Restraint System) ECU detects front passenger side airbag (typically seat side or curtain airbag) igniter circuit resistance below the calibrated threshold (normal range approximately 1.5-3.0 Ω; detected resistance <1.0 Ω or approaching 0 Ω). This fault indicates a short circuit risk in the airbag igniter circuit, which can cause: 1) Airbag deployment failure during a collision, resulting in loss of occupant protection; 2) Unintended airbag deployment due to the short circuit in extreme cases. The SRS enters fail-safe mode, illuminates the airbag warning light, and may disable the seat belt pretensioner function on some models.
B163B›
This DTC indicates a Parking Assist System (PAS/PSD) fault. Specifically, the Left Rear Ultrasonic Sensor detects an abnormally low resistance signal (typically <0.8kΩ or a short to ground). Normal ultrasonic sensor operating resistance ranges from 9-11kΩ. The sensor transmits and receives 40kHz ultrasonic signals to detect the distance to rear obstacles. The system sets this DTC when the sensor’s internal piezoelectric ceramic element shorts, wiring harness insulation chafes and grounds, connector water ingress shorts the signal wire to ground, or an incorrect sensor installation gap causes continuous false triggering. This fault prevents obstacle detection in the vehicle’s left rear blind spot, causes missing or false reversing sensor warning tones, and severely compromises parking safety. This DTC relates exclusively to the Parking Assist System, not the "front passenger side airbag" described in the original data. Airbag resistance faults typically trigger other codes (such as the B163C series).
B163B1A›
DTC B163B1A indicates the squib circuit resistance of the front passenger side airbag (typically mounted on the outboard side of the front passenger seat or inside the right front door trim panel) falls below the minimum threshold set by the SRS control module (ACM) (typically below 1.0-1.5 Ω; normal range is 2.0-3.0 Ω). This condition indicates a partial or complete short in the squib circuit. Damaged wiring, water ingress at the connector, or an internal airbag fault can cause this issue. This fault triggers the safety protection mechanism. The SRS system disables the airbag circuit to prevent unintended deployment and illuminates the airbag warning light on the instrument cluster. During a side impact, this airbag may fail to deploy normally, severely compromising occupant safety.
B163C-00›
This DTC indicates the airbag control unit (SRS ECU) detects the resistance of the front passenger side airbag (typically the seat side airbag or door side airbag) ignition circuit exceeds the calibrated threshold (normal value typically 2.0-3.0Ω, fault threshold typically >4.0Ω). This indicates a high-resistance condition in the ignition circuit, classified as a soft fault (precursor to an intermittent open circuit). Poor connector contact, a partially broken wiring harness, increased contact resistance in the clock spring (spiral cable), or aging of the internal resistance wire in the airbag module can cause this condition. This fault causes the SRS system to mark the airbag as unreliable. During a collision, the airbag may fail to deploy normally or experience a deployment delay. The system illuminates the airbag warning lamp and disables the airbag function, severely compromising passive safety performance.
B163C›
Fault code B163C has different definitions across BYD vehicle platforms. On early e-Platform 2.0 models (e.g., Yuan 2019, Song MAX 2019, Qin 2020), this fault code indicates excessive resistance in the front passenger side airbag. The SRS system detects that the right-hand Seat Side Airbag ignition circuit resistance exceeds the calibrated threshold (normal range: 2.0–3.0 Ω; fault threshold: >4.5 Ω). This condition can prevent proper airbag deployment during a collision. On newer e-Platform 3.0 and DM-i models (e.g., Han EV, Tang DM-i, Seal, Qin Plus), the ADAS system defines B163C as a Front Millimeter Wave Radar sensor signal fault or communication interruption. This fault indicates abnormal communication between the radar and the ADAS controller (ACC/ESP module) exceeding the specified time (usually >100 ms), or a radar self-check detecting an internal hardware fault (e.g., RF front-end anomaly or signal processing unit fault). This disables functions including Adaptive Cruise Control (ACC), Automatic Emergency Braking (AEB), and Intelligent Cruise Control (ICC). Poor wiring harness connections, airbag unit aging, or connector oxidation typically cause excessive resistance in the airbag system. Physical damage, water ingress, or incorrect installation angles typically cause radar system faults.
B163C1B›
DTC B163C1B indicates the front passenger side airbag igniter circuit resistance exceeds the normal threshold (typically 2.0–3.0 Ω). The system triggers this fault upon detecting resistance > 6 Ω or an open circuit. This fault falls under the SRS (Supplemental Restraint System) passive safety category, specifically indicating a high-resistance fault in the front passenger seat-mounted side airbag or curtain airbag electrical circuit. High resistance indicates poor circuit contact, a broken wiring harness, an oxidized connector, or an open airbag igniter. This condition may prevent proper airbag deployment during a collision, constituting a safety-related functional fault.
B1640-00›
This DTC indicates the Airbag Control Unit (ACU) detects an open circuit or abnormal resistance in the driver-side seat belt pretensioner circuit. The pretensioner contains a squib and a resistance wire; normal resistance typically measures 2.0-3.0Ω. The ACU triggers B1640-00 when it detects infinite resistance (open circuit) in the pretensioner circuit or when the resistance remains outside the threshold range for a specified time. During a collision, this fault may prevent the driver-side seat belt pretensioner from deploying and tightening, severely compromising occupant restraint protection. The fault also forces the SRS system into a degraded protection mode and continuously illuminates the airbag warning light.
B1640›
DTC B1640 indicates the SRS (Supplemental Restraint System) ECU detects an open circuit or out-of-range resistance in the driver-side seat belt pretensioner circuit (normal resistance is typically 2.0–3.0 Ω). The pretensioner is a key component of the passive safety system. During a collision, it ignites a pyrotechnic charge to generate gas, pulling the seat belt retractor and instantly tightening the seat belt to secure the occupant. This fault indicates the driver-side pretensioner may fail to deploy during a collision, increasing occupant forward displacement and injury risk. The SRS ECU also illuminates the instrument cluster airbag warning light. The system may enter a fail-safe mode, restricting certain airbag functions.
B16401B›
DTC B16401B indicates the Airbag Control Unit (ACU) detects the driver-side seat belt pretensioner circuit resistance falls outside the normal range (typically 2.0-3.0 Ω), indicating an open circuit or disconnected state. This active SRS fault means the driver-side seat belt pretensioner may fail to ignite and retract during a collision, increasing seat belt slack and reducing occupant restraint protection. The '1B' fault code suffix typically represents a specific subtype high-byte/low-byte coding, specifically denoting an open circuit or high-resistance fault. This fault illuminates the airbag warning light continuously. Some models may sound a warning buzzer and force the airbag system into a degraded protection mode, allowing only partial airbag deployment.
B2AB0-49›
DTC B2AB0-49 indicates an abnormality in the electric A/C compressor current sampling circuit. In electric compressors driven by a three-phase permanent magnet synchronous motor (PMSM), the controller (MCU) monitors the motor phase currents (U/V/W phases) in real time via a Hall effect sensor or precision shunt resistor for field-oriented control (FOC) and overcurrent protection. This fault indicates the sampling signal exceeds the valid threshold (open circuit, short circuit, or short to power/ground). Consequently, the compressor controller cannot accurately read the motor current value and triggers a protection mechanism to stop the compressor, impairing A/C cooling and battery thermal management functions. This is a hardware-level circuit fault, not a software logic error.
B1641-00›
DTC B1641-00 indicates an abnormal short to body ground in the driver-side seat belt pretensioner igniter circuit. In the BYD SRS (Supplemental Restraint System) architecture, a low-impedance igniter (normal resistance 2.1–3.0 Ω) triggers the pretensioner. When the ECU detects circuit resistance below the threshold (typically <0.8 Ω), it determines a short to ground. This fault causes the following: 1) The SRS system enters fail-safe mode, disabling the driver-side airbag and pretensioner functions; 2) The pretensioner may fail to deploy during a collision, causing occupant restraint failure; 3) Continuous short-circuit current risks unintended pretensioner deployment or SRS ECU driver circuit burnout. This DTC is a hard fault requiring physical repair before clearing.
B1641›
DTC B1641 indicates an abnormally low-resistance path to body ground (short circuit) in the driver-side seat belt pretensioner ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, the pretensioner is a pyrotechnic safety device with a normal squib resistance of approximately 2.0-3.0 Ω. The SRS control unit triggers this DTC when it detects the circuit resistance to ground falls below the threshold (typically <1.0 Ω). This fault forces the SRS into fail-safe mode: the airbag warning lamp remains illuminated, and the fault may completely disable the system. During a collision, the pretensioner fails to deploy and retract the seat belt, severely threatening occupant safety. Furthermore, a continuous short to ground can overheat and damage the internal driver circuit of the SRS control unit, expanding the repair scope.
B164111›
This DTC indicates the driver-side seat belt pretensioner ignition circuit shorts to body ground (GND). The BYD SRS (Supplemental Restraint System) pretensioner typically uses a pyrotechnic or motor-driven design with an operating resistance of approximately 2.0–3.0 Ω. When the ACU (Airbag Control Unit) detects the insulation resistance between the driver pretensioner circuit and ground drops below the threshold (typically <100 Ω), it logs a short to ground. This fault triggers the SRS fail-safe mode: the airbag warning light remains illuminated, the affected pretensioner may fail to deploy during a collision, and the system may stop monitoring other restraint devices, posing a severe safety hazard. The short circuit may occur at the pretensioner itself, the under-seat wiring harness, the floor wiring harness, or the ACU connector.
B1642-00›
DTC B1642-00 indicates the driver-side seat belt pretensioner ignition circuit shorts to the vehicle power supply (B+). In the BYD SRS (Supplemental Restraint System) architecture, the pretensioner operates as a pyrotechnic actuator. Normally, both terminals exhibit a high-resistance state (open circuit) to power and ground. This fault indicates a wire in the pretensioner harness or connector shorts to constant power. This condition can cause: 1) the SRS ECU to detect abnormal voltage, illuminate the airbag warning lamp, and disable the airbag system; 2) the pretensioner to deploy accidentally in extreme cases; 3) the pretensioner to fail during a collision, endangering occupant safety. This fault involves the dedicated yellow SRS harness under the driver's seat, an area prone to mechanical wear from fore-aft seat movement.
B1642›
DTC B1642 indicates a short to power (+B) in the driver seat belt pretensioner ignition circuit. The pretensioner is a key actuator in the SRS safety system containing a pyrotechnic igniter and a gas generator. Normal static resistance is approximately 1.5-3.0Ω. The SRS ECU sets this fault code upon detecting abnormal continuity between the pretensioner circuit and the vehicle power supply (12V constant power or IGN power). This fault presents two risks: first, it can cause the pretensioner to deploy and tighten unexpectedly while driving, startling or injuring the driver; second, during an actual collision, the power supply clamps the circuit, preventing the pretensioner from receiving sufficient ignition current and neutralizing its protective function. Additionally, this fault forces the SRS system into fail-safe mode, potentially disabling the entire airbag system.
B164212›
This DTC indicates an abnormal electrical connection between the driver-side seat belt pretensioner squib circuit and vehicle power positive (B+), causing the SRS control unit to detect a continuous high voltage (near 12V) across the pretensioner terminals. As a key actuator in the passive safety system, the pretensioner has a normal operating resistance of 2.0-3.0 ohms. The SRS ECU supplies a momentary deployment current only upon receiving a collision signal. A short to power causes the SRS ECU to immediately enter fault protection mode and disable all airbag deployment functions. During a collision, the pretensioner fails to deploy and tighten the seat belt. In extreme cases, the short circuit may trigger unintended pretensioner activation, severely threatening occupant safety. This is a hard fault; once confirmed, it typically does not self-recover.
B1645›
DTC B1645 indicates the driver-side seat belt pretensioner squib circuit resistance measures 0 Ω or close to 0 Ω, confirming a short circuit. The pretensioner is a critical SRS (Supplemental Restraint System) component. During a collision, it fires the squib to rapidly tighten the seat belt and secure the occupant in the seat. A 0 Ω resistance typically indicates an internal short circuit in the pretensioner squib, a wiring harness short to ground, bridged connector terminals, or a faulty internal driver circuit in the SRS control module. This fault forces the SRS into fail-safe mode and continuously illuminates the instrument panel airbag warning light. In a collision, the affected pretensioner will fail to deploy. This condition may also disrupt normal airbag deployment logic, creating a severe safety hazard.
B1645-00›
This DTC indicates the SRS control module detects the driver-side seat belt pretensioner squib circuit resistance at or near 0 ohms, indicating a short circuit. As a key actuator in the passive safety system, the pretensioner ignites the squib during a collision to generate gas and tighten the seat belt, eliminating slack between the occupant and the belt. A 0-ohm resistance indicates an internal short circuit in the squib, a short to ground in the wiring harness, or a fault in the internal driver circuit of the SRS module. This fault causes the SRS system to enter degraded mode. The driver-side airbag may fail to deploy properly, and the airbag warning lamp illuminates. On some BYD new energy models, similar DTCs may relate to the high-voltage system (such as the traction battery charging circuit). However, the official repair manual explicitly assigns B1645-00 to the SRS restraint system.
B1646-00›
DTC B1646-00 indicates the driver-side seat belt pretensioner circuit resistance is below the standard threshold set by the SRS control unit (typically 2.0Ω±0.1Ω). The pretensioner is a pyrotechnic actuator containing an igniter pellet and a heating wire; normal resistance is 1.5-3.0Ω. Low resistance typically indicates a short circuit (such as a short to ground, a wire-to-wire short, or an internal pretensioner short), reducing current path resistance. This fault forces the SRS system into a degraded mode. During a collision, the system may fail to deploy the driver-side pretensioner or, in extreme cases, cause unintended deployment, severely compromising passive safety system functionality.
B1646›
DTC B1646 indicates the SRS (Supplemental Restraint System) detects driver-side seat belt pretensioner circuit resistance below the calibrated threshold (typically <1.0Ω or near a short circuit). The pretensioner contains an internal squib with a normal resistance between 1.5 and 3.0Ω (depending on specific vehicle calibration). Low resistance indicates a short circuit risk. Potential causes include an inter-turn short within the pretensioner igniter, a wiring harness short to ground, or abnormal connector continuity. The SRS control unit classifies this fault as a high-risk condition, illuminates the airbag warning lamp, and may trigger the system self-protection mechanism (disabling the driver-side airbag and pretensioner). This prevents the seat belt from retracting properly during a collision, severely compromising passive safety functions.
B16461A›
This DTC indicates the measured resistance of the driver-side seat belt pretensioner ignition circuit falls below the SRS control module threshold (typically <1.0Ω). The seat belt pretensioner is a pyrotechnic actuator containing a resistance wire and ignition charge; normal resistance ranges from 2.0-5.0Ω. Low resistance typically indicates a circuit short to ground, a wire-to-wire short, a partial short in the pretensioner internal resistance wire, or grounded connector pins. This fault causes the SRS system to enter fail-safe mode. During a collision, the pretensioner may fail to deploy and tighten the seat belt, or in extreme cases, poses a safety risk of unintended deployment.
B167600›
This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit between the Left Rear Side Impact Sensor (typically installed on the left rear quarter panel or C-pillar area) and the main control unit. Specifically, during the ignition ON self-check or continuous monitoring while driving, the ECU detects the sensor circuit resistance exceeds the normal range (exhibiting high resistance or an open circuit) and fails to receive a valid acceleration signal. This fault causes the SRS system to disable deployment of the left side airbag and side curtain airbag. In a left-side collision, these airbags may fail to deploy, severely compromising passive safety performance. The vehicle drive system remains unaffected.
B1647-00›
This fault code indicates the airbag control unit (SRS ECU) detects the driver-side seat belt pretensioner circuit resistance exceeds the standard range (normal: 2.0-3.0Ω; high resistance generally indicates >5Ω or a near open circuit). The pretensioner contains an electrothermal igniter (squib). The ECU continuously monitors circuit resistance using a low-current signal to verify continuity. High resistance typically indicates high impedance or an open circuit. This condition may prevent the pretensioner from deploying and retracting the seat belt during a collision, severely compromising occupant protection. The SRS system enters fail-safe mode, illuminates the instrument cluster airbag warning light, and may disable the front airbags on certain models.
B1647›
DTC B1647 indicates the driver-side seat belt pretensioner circuit resistance exceeds the upper limit set by the SRS control unit (standard value typically 2.0-3.0 Ω; refer to the vehicle workshop manual). The seat belt pretensioner uses a pyrotechnic squib; its resistance reflects the electrical integrity of the firing element. High resistance indicates an additional high-impedance point in the circuit. Potential causes include an aging or broken internal pretensioner resistance wire, oxidized or corroded harness connectors, internal wire breaks, or poor contact. This fault causes the SRS system to deem the pretensioner circuit unreliable. During a collision, the pretensioner may fail to deploy, preventing the seat belt from retracting in time and severely compromising occupant protection.
B16471B›
DTC B16471B indicates the driver-side seatbelt pretensioner circuit resistance exceeds the normal threshold set by the SRS control module (typical normal range: 1.5-4.0 Ω; detected value is high). The pretensioner is a pyrotechnic component of the passive safety system, containing a resistance wire and an igniter charge. Excessive resistance indicates high circuit impedance resulting from poor contact, wiring harness oxidation, connector corrosion, or pretensioner aging. This fault forces the SRS system into a degraded mode and continuously illuminates the airbag warning light. During a collision, the driver-side seatbelt pretensioner may fail to deploy and retract, severely compromising occupant restraint protection.
B164A-00›
This DTC indicates the airbag control unit (SRS ECU) detects an open circuit or abnormal resistance in the front passenger seat belt pretensioner circuit. Specifically, the ECU continuously monitors the pretensioner deployment circuit resistance via an internal bridge circuit (standard range: 1.6–3.0 Ω). The ECU triggers DTC B164A-00 if it detects a resistance >6 Ω (open circuit) or <1 Ω (short circuit), or a communication interruption with the pretensioner. As an active safety device, the pretensioner uses a pyrotechnic gas generator to generate tension within approximately 15 milliseconds of a collision, instantly retracting the seat belt webbing to eliminate slack against the occupant. This fault indicates complete failure of this protective function. Per the BYD SRS safety strategy, the system may enter a degraded mode (e.g., disabling side or curtain airbags), significantly increasing the risk of injury to the front passenger during a collision.
B164A›
DTC B164A indicates the SRS (Supplemental Restraint System) electronic control unit detects abnormal resistance in the deployment circuit of the front passenger seat belt pretensioner (or driver-side airbag, depending on vehicle configuration), identifying an open circuit (disconnected). The SRS system continuously monitors the circuit resistance of the airbag/pretensioner gas generator (normal value approximately 2-3 Ω, including the series diagnostic resistor) to ensure reliable ignition during a collision. The ECU triggers DTC B164A when it detects infinite resistance (>6 Ω) or a communication interruption. This fault prevents the deployment circuit from firing correctly during a collision, illuminates the airbag warning light continuously, and forces the system into fail-safe mode. On some BYD models, DTC B164A specifically indicates a driver airbag (DAB) circuit fault. The underlying issue remains the same type of abnormal connection in the deployment circuit.
B164A1B›
This fault code indicates the Supplemental Restraint System (SRS) detected an open circuit or high resistance condition in the front passenger seat belt pretensioner circuit (resistance value outside the calibrated range of 2-5Ω). As a key actuator in the passive safety system, the seat belt pretensioner contains a pyrotechnic device. During a frontal collision, electronic detonation generates a reaction force to rapidly tighten the seat belt and remove slack between the occupant and the belt. Fault code B164A1B indicates the SRS control unit (ACU) cannot establish an effective electrical connection with the front passenger pretensioner. This condition prevents the pretensioner from deploying during a collision, continuously illuminates the instrument cluster airbag warning light, and forces the system into a degraded protection mode. Some models may also limit power output or disable other associated safety functions.
B164B-00›
DTC B164B-00 indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance path (typically <1Ω) from the front passenger seat belt pretensioner ignition circuit to body ground. The pretensioner is a pyrotechnic safety device containing an igniter and a gas generator, with a normal resistance of approximately 2.0-3.0Ω. A short to ground indicates damaged insulation on at least one of the two ignition circuit wires contacting vehicle body metal, or an internal short circuit within the pretensioner igniter. The system classifies this fault as severe because: 1) the short circuit can cause unintentional pretensioner deployment, injuring the occupant; 2) it can prevent pretensioner deployment during a collision, causing a loss of restraint protection; 3) the SRS system enters fail-safe mode, which can disable the front airbags.
B165D›
DTC B165D indicates the airbag control unit (ACU/SRS ECU) detects an open circuit in the right front impact sensor (RFIS) communication circuit. The ECU fails to receive a valid signal from the sensor within the specified monitoring period or detects infinite circuit resistance. Typically mounted on the right front side member (behind the headlamp or inside the fender), the sensor detects collision acceleration at the right front of the vehicle. This fault forces the airbag system into degraded mode. In a frontal collision, the ACU may fail to accurately determine impact severity. This failure delays or prevents the deployment of passive safety devices, such as airbags and seat belt pretensioners, severely increasing occupant injury risk. The vehicle remains drivable, but safety protection functions are compromised.
B164B›
DTC B164B indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance path (typically <1.5Ω) between the front passenger seat belt pretensioner ignition circuit and body ground (GND). As a pyrotechnic safety device, the pretensioner igniter has a normal resistance of approximately 2.0-3.0Ω. A short to ground causes the SRS system to detect a front passenger pretensioner circuit fault, illuminate the 'Airbag Fault Warning Light' continuously, and enter fail-safe mode. During a collision, the system may fail to deploy the front passenger pretensioner and may subsequently disable the front passenger airbag. This fault is a hard short to ground. Repair immediately to ensure passive safety system integrity.
B164B11›
This DTC indicates the SRS (Supplemental Restraint System) control unit detected a short to ground in the front passenger seat belt pretensioner ignition circuit. The seat belt pretensioner is a pyrotechnic safety device containing a gas generator and a resistance wire igniter, with a normal operating resistance of approximately 1.5-2.5Ω. The BYD diagnostic protocol defines the DTC suffix '11' as a short to ground fault. The SRS module sets this code when it detects pretensioner circuit resistance below the threshold (typically <1.0Ω) or abnormal voltage to ground. This fault forces the SRS into a degraded mode, disables the front passenger pretensioner, and illuminates the instrument cluster airbag warning lamp. Because the pretensioner contains pyrotechnics, a short circuit risks accidental deployment or failure during a collision. Address this highest safety level (Level 3) fault immediately.
B164C-00›
This DTC indicates an abnormal short circuit between the front passenger seat belt pretensioner ignition circuit and the vehicle power supply (+B, typically the positive terminal of the 12V battery). The pretensioner is a pyrotechnic device. During a collision, the SRS control unit sends an ignition signal to trigger the internal gas generator and rapidly tighten the seat belt. A short to power in the pretensioner circuit indicates damaged wiring insulation or internal connector bridging, applying a continuous high potential across the pretensioner terminals. This condition forces the SRS system into fail-safe mode, disabling the front passenger airbag and pretensioner functions. Extreme cases risk unintended pretensioner deployment or complete failure, posing a severe safety hazard.
B164C›
DTC B164C indicates an unintended electrical connection between the front passenger-side seat belt pretensioner control circuit and the vehicle power supply (B+). The seat belt pretensioner is a key actuator in the SRS system and contains a pyrotechnic device. Under normal conditions, the airbag ECU triggers the pretensioner only during a collision via a low-level signal. A short to power continuously exposes the pretensioner supply or control circuit to 12V. This fails the system self-check, illuminates the SRS warning lamp, and creates a severe safety risk: the short-circuit current may accidentally trigger the pretensioner (instantly and permanently locking the seat belt), or circuit protection mechanisms may prevent proper pretensioner deployment during a collision. Repair this hard short-circuit fault immediately to ensure full passive safety system functionality.
B164C12›
DTC B164C12 indicates the airbag control unit (SRS ECU) detects an abnormally low-impedance connection between the front passenger seat belt pretensioner drive circuit and the vehicle power supply (B+). The pretensioner is essentially an electric squib with a normal operating resistance of approximately 2.0-3.0Ω. When damaged wiring harness insulation causes contact with a constant power wire, the ECU detects an abnormal voltage (approaching 12V/B+ voltage) instead of the expected open circuit or low-resistance state. This fault triggers the SRS fail-safe mode. The system disables the front passenger airbag and pretensioner functions to prevent injury from accidental deployment, and illuminates the airbag warning light to alert the driver. Excessive short-circuit current also risks unintended pretensioner deployment or burning out the SRS driver chip.
B164F-00›
B164F-00 indicates the measured resistance of the front passenger seat belt pretensioner is 0 ohms, signifying a short circuit fault in the pretensioner circuit (short to ground or internal short). In the SRS (airbag) system, normal pretensioner resistance is typically 2.0-3.0 ohms. The ECU monitors circuit current to determine component status. A 0-ohm resistance indicates an abnormal current path. The ECU registers a short circuit fault, illuminates the airbag warning light, and may disable the passenger airbag and pretensioner functions, severely compromising occupant protection during a collision. Differentiate this fault from "resistance too high" (open circuit). A 0-ohm reading typically indicates a hard short circuit or a direct harness short to ground.
B164F›
DTC B164F indicates the measured circuit resistance of the front passenger side (front right) seat belt pretensioner is 0 ohms. In BYD SRS (Supplemental Restraint System) circuit logic, a 0-ohm resistance typically indicates a short to ground or a low-impedance short, rather than an open circuit. The pretensioner contains a squib and heating wire; normal resistance is 1.5-3.0 Ω. This fault causes the SRS control module to register an abnormal pretensioner circuit, meaning the pretensioner may fail to tension the seat belt during a collision. The instrument cluster AIRBAG/SRS warning light remains illuminated, the system enters fail-safe mode, and the SRS module may simultaneously disable the front airbags, severely compromising occupant protection.
B164F1A›
DTC B164F1A indicates the Airbag Control Unit (ACU) detects a front passenger seat belt pretensioner circuit resistance of 0 ohms or close to 0 ohms, determining a short circuit fault. The pretensioner contains a pyrotechnic squib with a normal resistance between 1.5 and 3.0 Ω. A resistance of 0 indicates an internal short circuit in the pretensioner, a wiring harness short to ground, or a pin-to-pin short at the connector. This fault prevents the SRS system from triggering the front passenger seat belt pretensioner during a collision (failing to tighten the seat belt). In extreme cases, the short circuit illuminates the airbag warning light continuously and locks the entire airbag system, severely compromising passive safety performance.
B1650-00›
DTC B1650-00 indicates the passenger seat belt pretensioner circuit resistance falls below the normal threshold set by the SRS control module (typically <2.0Ω; normal range is 2.0-3.0Ω). The pretensioner contains a pyrotechnic squib. The ECU continuously monitors the squib resistance using a low-current signal. Low resistance typically indicates a short to ground in the squib circuit, a ground fault from damaged wiring insulation, an internal connector short, or an internal short within the pretensioner component. This fault forces the SRS system into a degraded mode, meaning the pretensioner may fail to deploy during a collision (seat belt fails to tighten) or may deploy inadvertently (unexpected firing). ISO 15031 and BYD safety system design classify this as a Level 2 safety fault requiring immediate repair.
B1650›
DTC B1650 indicates the SRS (Supplemental Restraint System) control module detects the front passenger-side seat belt pretensioner igniter circuit resistance is below the calibrated threshold (typically <1.0 Ω; normal range: 2.0-3.0 Ω). This indicates a potential short circuit in the internal pretensioner bridge wire, or a short to ground or wire-to-wire short in the harness. This fault prevents the SRS from triggering the front passenger seat belt pretensioner during a collision (loss of pretensioning protection), or creates a risk of unintended deployment in extreme cases. The system illuminates the airbag warning lamp and may disable the front passenger airbag deployment function. In some BYD model years, this code may also indicate an Occupant Classification System (OCS) communication fault. However, based on the provided fault context, prioritize checking the pretensioner assembly and its wiring harness resistance.
B16501A›
DTC B16501A indicates the airbag system (SRS) detects the front passenger seat belt pretensioner resistance is below the calibrated threshold (typically below 1.0Ω-1.5Ω; normal range is approximately 2.0Ω-3.5Ω; refer to the repair manual for exact specifications). The seat belt pretensioner is a pyrotechnic actuator containing a resistance wire (squib) and an ignition charge. Low resistance typically indicates an internal short circuit in the pretensioner, a wiring harness short to ground, a short between connector terminals, or a sampling circuit fault in the SRS control module (ACU). This fault causes the SRS to register a pretensioner circuit fault, illuminate the airbag warning lamp, and potentially fail to deploy the front passenger seat belt pretensioner during a collision, severely compromising occupant protection.
B1651-00›
This DTC indicates the airbag control unit (SRS ECU) detects the front passenger seat belt pretensioner circuit resistance exceeds the calibrated upper limit (typically >3.5Ω, standard value approximately 2.0Ω±0.4Ω). Electrically, the pretensioner is essentially a squib consisting of a resistance wire and an igniter charge. High resistance usually indicates high impedance or an open circuit. Potential causes include a partially blown internal resistance wire in the pretensioner, increased connector contact resistance, or a hidden open circuit in the wiring harness. This fault causes the SRS system to enter degraded mode: during a frontal collision, the front passenger seat belt fails to pretension automatically, and the system may suppress the front passenger airbag deployment strategy, severely compromising passive safety performance.
B1651›
DTC B1651 indicates the Airbag Control Unit (ACU) detects the front passenger-side seat belt pretensioner circuit resistance exceeds the calibrated threshold (typically above 4.8Ω or open circuit). The pretensioner utilizes a squib structure with a normal resistance of 2.0±0.3Ω. Excessive resistance indicates a high-resistance or open-circuit risk in the firing circuit. During a collision, this prevents the ACU from reliably triggering the pretensioner, leaving the seat belt unable to tighten promptly and severely compromising occupant protection. This constitutes a Level 2 SRS fault. The system illuminates the airbag warning lamp and may force the front passenger airbag into a degraded protection mode.
B16511B›
This DTC indicates the SRS (Supplemental Restraint System) detects the front passenger-side seat belt pretensioner squib resistance exceeds the system calibration threshold (typically >4Ω or near open circuit). The pretensioner is a critical component of the airbag system. During a collision, it fires a pyrotechnic charge to rapidly tighten the seat belt and eliminate slack between the occupant and the belt. High resistance indicates the ECU may fail to supply sufficient current to deploy the pretensioner during a collision. This deprives the front passenger of pretensioner protection and increases injury risk. This is a hard fault. The SRS warning lamp remains illuminated and the system enters degraded mode.
B2A5113›
DTC B2A5113 indicates an open circuit in the signal circuit of the A/C system low-pressure line pressure-temperature (PT) sensor. This sensor typically mounts on the low-pressure line between the evaporator outlet and the compressor inlet. It monitors low-side refrigerant pressure and temperature in real time, providing a key input signal to the heat pump/A/C control unit (integrated into the right domain controller or A/C controller) for compressor speed regulation, system protection, and thermal management. When the controller detects the sensor signal voltage continuously exceeding the normal range (typically 0.5-4.5V) or a communication interruption, it sets this open circuit fault. The system then triggers a protection mechanism and forces the electric compressor to stop, resulting in a complete loss of A/C cooling and heating functions. In extreme cases, this affects the battery pack cooling circuit and creates an overheating risk.
B1654-00›
DTC B1654-00 indicates a communication interruption or abnormal signal between the airbag control unit (SRS ECU) and the left front impact sensor. This sensor typically mounts inside the left front fender or on the longitudinal beam. It uses a two-wire communication circuit (signal wire and ground wire) and contains a piezoelectric or MEMS accelerometer with a normal resistance of approximately 2-3 kΩ. The ECU sets this DTC if it cannot detect the sensor feedback signal during a self-test or drive cycle, if the resistance falls outside the calibrated range (open or short circuit), or if communication verification fails. This fault disables the left front collision detection zone. During a collision, it may prevent accurate airbag deployment or cause unintended deployment, making it a safety-critical fault.
B1654›
DTC B1654 indicates the SRS (Supplemental Restraint System) ECU detected a communication interruption or abnormal circuit impedance between the Left Front Impact Sensor and the main controller during self-check or operation. This sensor typically mounts to the left front longitudinal beam, headlamp bracket, or fender reinforcement beam to monitor collision acceleration on the left front side of the vehicle. The ECU sets this DTC if it fails to receive a valid signal from the sensor within a predetermined time, or if it detects an open or short circuit in the wiring. Under this condition, the airbag system enters fail-safe mode, potentially disabling the left front collision detection function. This compromises the deployment logic of the airbags and seatbelt pretensioners during a frontal collision, posing a major safety risk.
B165400›
DTC B165400 indicates the airbag control unit (SRS ECU) detects a communication interruption with the Left Front Impact Sensor during a self-test or drive cycle. This sensor typically mounts on the left front longitudinal member (inside the fender or near the headlamp bracket) and detects front collision acceleration signals. "Not connected" indicates a disconnected physical plug, an open circuit in the sensor power/ground wiring, an open CAN/LIN communication line, an internal sensor open circuit, or a poor connection at the ECU connector. An active fault forces the SRS system into a degraded mode. This condition may prevent the left front airbag, driver airbag, or seatbelt pretensioner from deploying correctly during a collision, and illuminates the instrument cluster airbag warning light (flashing or solid).
B1655-00›
DTC B1655-00 indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance path (typically <10Ω) between the left front impact sensor (FIS) signal circuit and body ground. In the BYD SRS architecture, this sensor is typically a piezoelectric acceleration sensor. It communicates with the SRS ECU via a shielded twisted-pair wire and operates on a 2.5V reference bias voltage. A short to ground causes the ECU to continuously receive a 0V low-level signal, potentially causing the following: 1) the system misinterprets the condition as a sensor fault, enters fail-safe mode, and disables airbag deployment; 2) in extreme cases, intermittent changes in short-circuit resistance may cause unintended airbag deployment. This is a hard-wire fault, not a communication fault. It directly affects the trigger logic for the driver front airbag and seat belt pretensioner.
B1655›
DTC B1655 indicates a short to ground in the Left Front Impact Sensor signal circuit. In the BYD SRS (Supplemental Restraint System) architecture, this sensor typically mounts on the left front longitudinal beam or bumper reinforcement to detect frontal collision acceleration. A short to ground means the resistance between the sensor signal wire (usually the positive or communication wire) and the vehicle body ground drops abnormally (<1Ω). This prevents the SRS control module (ACU) from receiving a valid acceleration signal or causes it to continuously receive a 0V level. This fault forces the airbag system into fail-safe mode: during a collision, the system may fail to deploy the left front airbag and side curtain airbag, or extreme signal interference could cause unintended deployment. ISO 26021 classifies this as a Class A passive safety system fault. Immediately remove the vehicle from service to avoid safety risks.
B165511›
B165511 is a BYD SRS (Supplemental Restraint System / airbag system) circuit diagnostic trouble code. B1655 specifically designates the Left Front Frontal Impact Sensor circuit, and 11 is the subtype code indicating a Short to Ground. This fault indicates the SRS control module detects an abnormally low-resistance path (typically less than 1 ohm) between the left front impact sensor signal circuit and vehicle body ground, preventing the control module from correctly receiving the sensor acceleration signal. This fault forces the airbag system into fail-safe mode and continuously illuminates the instrument panel SRS warning light. During a collision, this condition may prevent the left front airbag from deploying normally or delay its deployment. This constitutes a severe fault affecting occupant safety.
B165600›
This fault code indicates the SRS (airbag) control module detects an abnormal signal from the Left Front Impact Sensor or an internal sensor fault. The Left Front Impact Sensor mounts to the front section of the left front longitudinal rail or near the headlamp bracket to detect deceleration changes during a frontal collision. The SRS module sets DTC B165600 when it detects a sensor signal voltage outside the normal range (typically 0.5-4.5V), a signal interruption, or an internal sensor self-check failure. This fault degrades frontal collision protection. In extreme cases, it may prevent the front airbags from deploying correctly during a collision or cause unintended deployment. The sensor uses a piezoelectric or capacitive accelerometer and communicates with the SRS module via a hardwired connection. The fault may involve the 12V sensor power supply, ground, or signal circuit (PWM or analog signal).
B165700›
DTC B165700 indicates abnormal configuration parameters for the Left Front Impact Sensor. This sensor is a critical component of the SRS (Supplemental Restraint System/Airbag System) and detects frontal collision acceleration. "Parameter error" indicates the calibration data, configuration code, or communication protocol stored within the sensor does not match the SRS control module (ACU), or the sensor's physical installation angle/position deviates from the design specification. This fault may cause: 1) Delayed or failed airbag deployment during a collision; 2) Unintended airbag deployment in non-collision scenarios; 3) Vehicle high-voltage interlock shutdown (some models cut off high voltage upon detecting abnormal collision signals). Unlike DTC B165600 (hardware fault) and B165800 (communication fault), this fault relates specifically to data configuration and installation geometry parameters.
B165800›
This DTC indicates a communication link fault between the SRS (Supplemental Restraint System) control unit and the Left Front Impact Sensor (LFIS). This typically indicates an interrupted LIN bus or private CAN communication between the sensor and the Airbag Control Module (ACM), a data validation failure, or a signal timeout. The LFIS monitors deceleration changes in the vehicle's left front area and provides the SRS control unit with critical collision severity data to determine whether to deploy the driver airbag, left curtain airbag, and seatbelt pretensioner. This communication fault prevents the control unit from receiving collision information for this zone. Consequently, it may cause unintended airbag deployment (fail-safe mode) or delay or prevent the activation of left-side protection devices during an actual collision. This constitutes a critical fault in the active safety system.
B165D-00›
DTC B165D-00 indicates a communication link interruption between the Supplemental Restraint System (SRS) Electronic Control Unit (ECU) and the Right Front Frontal Impact Sensor (RFFIS). In BYD vehicle architectures, this sensor typically features a 2-wire (signal loop) or 3-wire (power/signal/ground) design. It communicates via a hard-wired connection through the SRS ECU G10 connector, specifically the G10-3 signal terminal and G10-14 return terminal. The ECU sets this DTC if it detects the sensor circuit resistance exceeds the threshold (open circuit >10kΩ or short circuit <200Ω) during a monitoring cycle, or if it receives no valid sensor data for 3 consecutive monitoring cycles. This fault forces the SRS into a degraded mode, disabling the right-side frontal collision detection function. During a frontal impact, the system may delay or fail to deploy the right front airbag and right-side seat belt pretensioner. The instrument cluster SRS warning light remains illuminated to indicate a system fault.
B165D00›
DTC B165D00 indicates the airbag control unit (SRS ECU) detects a communication interruption or physical connection loss with the Right Front Frontal Impact Sensor. This sensor typically mounts inside the right front bumper reinforcement beam or at the front of the right fender to monitor collision acceleration at the right front of the vehicle. The SRS ECU sets this fault code if it fails to receive a valid signal from the sensor within a predefined cycle, or if it detects an open circuit or abnormal resistance in the sensor circuit. The airbag system then enters fail-safe mode, which may prevent the right front airbag, side airbag, or seat belt pretensioner from deploying normally during a collision. The instrument cluster airbag warning light remains illuminated, and some models may sound a warning buzzer.
B165E-00›
DTC B165E-00 indicates an abnormally low-impedance connection (short to ground) between the airbag system (SRS) right front impact sensor signal or power circuit and body ground (GND). This sensor typically mounts on the right front side member, radiator support, or fender reinforcement to detect collision acceleration on the right front side of the vehicle. A short to ground prevents the SRS control unit (ACU) from correctly reading the sensor's acceleration signal output (typically an analog or digital signal from a piezoelectric or MEMS sensor). This causes the following conditions: 1) airbags failing to deploy during an actual collision; 2) the system entering fail-safe mode and illuminating the SRS warning lamp; 3) in extreme cases, abnormal signals causing unintended airbag deployment. This safety-critical fault requires immediate repair.
B165E›
DTC B165E indicates the Right Front Impact Sensor detects a low-impedance or zero-impedance circuit, meaning the sensor signal wire or power wire is shorted to body ground. This piezoelectric acceleration sensor monitors collision deceleration at the front right side of the vehicle. A short to ground prevents the SRS ECU from receiving the correct collision signal and triggers a Level 3 severe fault: 1) the right-side airbag and seat belt pretensioner may fail to deploy in time during a collision; 2) the system may falsely report a collision signal, causing unintended deployment; 3) the entire SRS system enters fail-safe mode, restricting all airbag functions. Typical causes for this fault include damaged wiring harness insulation, water ingress in the connector, an internal sensor short circuit, or an ECU drive circuit fault.
B165E11›
DTC B165E11 indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance path (typically <1Ω) between the right front impact sensor signal or power circuit and body ground, constituting a short to ground. In BYD E2/E3/Qin EV architectures, this sensor utilizes a bipolar MEMS accelerometer and communicates with the SRS ECU via a hardwire or LIN bus connection. A short to ground causes the ECU to continuously receive a 0V reference signal, preventing it from distinguishing between "no collision" and "circuit fault" states. Per ISO 26262 functional safety requirements, the system enters Fail-Safe mode: it immediately illuminates the airbag fault warning lamp and disables right front airbag and side curtain airbag deployment to prevent unintended triggering or failure to deploy. This represents a severe ASIL-D fault.
B165F00›
DTC B165F00 indicates the SRS (Supplemental Restraint System) ECU detected a functional fault or communication error in the right front impact sensor. This sensor mounts near the right front side member or bumper reinforcement beam. It detects deceleration changes during a frontal collision and sends a crash signal to the airbag control unit. The '00' in the fault code typically indicates an internal sensor self-test failure, an out-of-range signal, or a communication interruption between the sensor and the ECU (non-specific short or open circuit). This fault disables the right front crash detection circuit. During a frontal collision, this failure may delay or prevent the deployment of the right front airbag and side curtain airbags, severely compromising passive safety performance. Consequently, the SRS illuminates the airbag warning light and may disable related airbag functions.
B166000›
DTC B166000 indicates the airbag control unit (SRSECU) detects the internal parameters of the Front Right Impact Sensor exceed the calibrated tolerance range. This sensor typically uses a MEMS capacitive or piezoelectric accelerometer to detect collision deceleration at the front right of the vehicle. "Parameter error" specifically indicates the sensor self-check detected sensitivity drift, zero offset exceeding the ±5% standard value, an abnormal temperature compensation curve, or corrupted calibration data stored in the EEPROM. This fault prevents the ECU from accurately interpreting the analog/digital signals transmitted by the sensor, potentially causing delayed deployment, non-deployment, or unintended deployment of the airbag during a collision (although unintended deployment probability remains low because the ECU utilizes a multi-sensor fusion algorithm). This represents a critical safety fault in the SRS system.
B166100›
DTC B166100 indicates a communication interruption or data abnormality between the Airbag Control Unit (ACU) and the Front Right Impact Sensor. The sensor mounts on the right front longitudinal beam or the right side of the bumper reinforcement beam to detect front-right collision acceleration. This communication error prevents the ACU from receiving real-time collision signals from this area, forcing the airbag system into a degraded mode. During a frontal collision, the system cannot accurately determine impact severity and direction, delaying or preventing deployment of the front right airbag and right-side pretensioner, which severely compromises occupant protection. This fault constitutes an active safety system failure and requires immediate repair.
B1666-00›
DTC B1666-00 indicates the Airbag Control Unit (ACU) detected a communication loss or abnormal signal from the Left Side Impact Sensor (LSIS). This sensor, typically located in the left B-pillar or left front door area, monitors vehicle side-impact acceleration. Root causes include: 1) Open circuit in the sensor power or ground lines; 2) Open circuit, short circuit, or short to ground in the communication harness (LIN bus or hardwire); 3) Failure of the sensor internal piezoelectric accelerometer or signal processing circuit; 4) Incorrect sensor installation causing the signal to fall outside the calibrated range. This safety-critical fault may prevent the left side airbag and curtain airbag from deploying during a side impact, or cause unintended deployment during normal driving.
B1666›
This DTC indicates interrupted communication or a physical disconnection between the airbag control unit (SRS ECU) and the Left Side Impact Sensor. The Left Side Impact Sensor typically mounts in the lower left B-pillar or the left front seat side trim area. It monitors left-side collision acceleration signals and provides key input for side airbag deployment decisions (including side airbags and side curtain airbags). The ECU records B1666 if it fails to receive the sensor ID response code within the specified monitoring period, if LIN bus communication times out, or if it detects an open power or ground circuit. This fault forces the left-side airbag system into fail-safe mode. During a side impact, the airbags may fail to deploy or deploy late, severely compromising occupant side-impact protection. Additionally, the instrument panel SRS warning lamp (airbag warning light) illuminates continuously, and the system may report the safety system fault status to the vehicle control unit via the CAN bus.
B166600›
DTC B166600 indicates a communication interruption between the SRS (Supplemental Restraint System) ECU and the left side impact sensor, or circuit resistance exceeding the calibrated range (typically >10kΩ or open circuit). On BYD E2/E3/Qin series models, the left side impact sensor mounts below the left B-pillar or on the left front door inner sheet metal to monitor left-side impact acceleration. The ECU triggers this DTC and illuminates the airbag warning lamp upon detecting a continuous open sensor signal circuit, an open internal sensor circuit, or an abnormal sensor power/ground circuit. Under this condition, side and curtain airbags may fail to deploy, but front airbag function usually remains unaffected.
B1667-00›
DTC B1667-00 indicates the airbag control unit (SRS ECU) detects a short to body ground in the signal circuit of the left side impact sensor (typically installed inside the left B-pillar reinforcement panel). This sensor is typically a MEMS capacitive or piezoelectric accelerometer. During normal operation, it returns a bias resistance of approximately 2.1-2.9 kΩ and a signal voltage of approximately 2.5 V to the ECU. When wiring harness insulation breaks, water enters the connector, or the sensor shorts internally, the ECU detects a continuous voltage signal below 0.5 V (short-to-ground threshold) and triggers this DTC. This fault disables the trigger threshold determination for the left side airbag and curtain airbag. During a side collision, the airbags may fail to deploy promptly, or signal interference during normal driving may cause unintended deployment. This is a highest-level safety fault.
B1667›
System definitions for DTC B1667 vary across BYD models. Original documentation classifies it under the SRS as "left side impact sensor short to ground." However, in practice for BYD F3, G6, S6, S7, Song, Tang, and Qin series models, B1667 generally indicates a Body Control System fault: "driver side (left) door mirror vertical adjustment motor fault/stuck." Based on circuit operation, the BCM (Body Control Module) identifies the fault by monitoring the drive current and position feedback signal of the door mirror vertical adjustment motor. The BCM stores this DTC when it detects a short to ground, abnormal current (too high or too low), motor stall, or an open circuit in the motor circuit. This fault disables the electric vertical adjustment of the door mirror. It typically does not affect horizontal adjustment, mirror heating, or folding functions (if equipped).
B166711›
DTC B166711 indicates a short to ground in the signal circuit of the airbag system (SRS) left side impact sensor. This sensor typically mounts inside the driver-side B-pillar trim panel and detects left-side impact acceleration. The SRS control unit sets this fault when it detects abnormal voltage to ground on the sensor signal wire (continuous low level) or a resistance value below the threshold. This fault causes the airbag system to enter fail-safe mode. During a side collision, the left side airbag and left curtain airbag may fail to deploy. The instrument panel continuously illuminates the airbag warning light. The BYD diagnostic protocol defines the DTC suffix '11' as 'Shorted to Ground', distinguishing it from '00' (open circuit/not connected) or other fault types.
B166800›
DTC B166800 indicates a functional fault in the Left Side Impact Sensor within the Supplemental Restraint System (SRS). This sensor typically mounts inside the left B-pillar trim panel or near the left side sill beam. It contains a built-in accelerometer to detect side-impact acceleration on the left side of the vehicle. When the sensor detects acceleration exceeding a specific threshold, it sends a crash signal to the SRS ECU, which then determines whether to deploy the left side airbag and side curtain airbag. This DTC triggers when the SRS ECU continuously fails to receive a valid signal from the sensor (due to communication loss, abnormal signal voltage, or sensor unresponsiveness), disabling the left-side impact protection function. In this fault state, the side airbag and side curtain airbag may fail to deploy during a side collision, severely endangering occupant safety.
B166900›
This fault code indicates the SRS (Supplemental Restraint System) control module detects the configuration parameters for the left side impact sensor (typically mounted on the left B-pillar, left front door intrusion beam, or under the driver's seat, depending on vehicle configuration) do not match expected system values. This is not a simple electrical open/short circuit (DTC B166800) or communication interruption (DTC B166A00). Instead, it indicates the SRS control module EEPROM contains abnormal or missing data for the sensor's hardware ID code, calibration coefficients, software version identifier, or installation position parameters. Specifically, the control module cannot correctly identify the sensor. This may cause the side airbag and curtain airbag deployment thresholds to deviate from design values, or cause the system to fail to deploy during a side impact. Common trigger scenarios include: failing to perform online configuration (coding) after sensor replacement, failing to migrate data after an SRS control module software update, using non-genuine parts (lacking vehicle configuration data), or SRS module data area damage following a collision. This fault is a functional safety configuration error. Repair immediately to restore normal side impact protection function.
B166A00›
DTC B166A00 indicates interrupted communication or abnormal data between the airbag control unit (SRS ECU) and the Left Side Impact Sensor. This sensor typically mounts at the lower B-pillar or under the left front seat and monitors left-side impact acceleration. A communication error prevents the ECU from receiving real-time impact data from the sensor, causing the side and curtain airbags to fail to deploy accurately during a collision, or risking unintended deployment. This fault constitutes an active safety system failure. The vehicle remains drivable, but side-impact protection functions degrade.
B166F-00›
DTC B166F-00 indicates the airbag control unit (SRS ECU) detects a communication loss or electrical disconnection with the right side impact sensor. This sensor typically mounts in the right B-pillar or inside the door to monitor side-impact acceleration and serves as the key input device to trigger the right side airbag and curtain airbag. The ECU sets this fault code if it fails to receive a valid signal from the sensor within the set cycle, or detects an open or short circuit in the wiring. This fault forces the right side airbag system into fail-safe mode. The airbags may fail to deploy during a side impact, severely compromising occupant passive safety. The instrument cluster continuously illuminates the SRS warning light.
B166F›
DTC B166F indicates a loss of communication between the SRS (Supplemental Restraint System) ECU and the Right Side Impact Sensor (RSIS). This sensor typically mounts below the B-pillar on the right front door frame or the lower section of the right centre pillar to detect side-impact acceleration on the right side of the vehicle. The SRS ECU sets this fault code if it fails to receive a signal from the sensor within a predetermined time, or detects circuit resistance outside the normal range (open/short circuit). This fault may prevent the right side airbag and right curtain airbag from deploying correctly during a side impact, severely compromising occupant side-impact protection. It does not affect frontal impact protection.
B166F00›
This fault code indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit at the right side impact sensor. The sensor typically mounts inside the right front door trim panel or below the B-pillar and monitors the right-side collision acceleration signal. The SRS ECU triggers DTC B166F00 if it fails to receive a valid signal from the sensor within the preset monitoring period or detects an open circuit in the sensor power or communication lines. This fault may prevent the side airbag and side curtain airbag from deploying correctly during a side impact, but does not cause accidental deployment. The system illuminates the instrument cluster SRS warning light to indicate a safety system fault.
B1670-00›
DTC B1670-00 indicates an abnormally low-resistance connection between the right side impact sensor (SIS) signal circuit and body ground, resulting in a short to ground. The BYD SRS (Supplemental Restraint System) architecture utilizes a piezoelectric or MEMS accelerometer for the right side impact sensor. This sensor mounts inside the right B-pillar or the right front or rear door cavity and monitors side impact acceleration. A short to ground prevents the SRS control unit (ACU) from receiving a valid analog acceleration signal (typically a 0.5-4.5V voltage signal). Instead, the ACU receives a ground potential near 0V. This condition triggers the ACU to enter fault protection mode, disable the right side airbag and curtain airbag deployment, and illuminate the airbag fault warning lamp. If the short circuit occurs during an impact, it can cause unintended airbag deployment or failure to deploy, creating a serious safety hazard.
B1670›
DTC B1670 indicates an abnormally low-resistance connection (short to ground) between the right Side Impact Sensor (SIS) signal circuit and body ground (GND). Electrically, this typically indicates damaged signal wire insulation contacting body metal, an internal connector short, or a sensor internal integrated circuit fault shorting the signal output terminal to the housing. This fault causes the Airbag Control Unit (ACU) to continuously receive a false 'crash trigger' signal (voltage near 0V) or completely lose sensor communication. Consequently, the ACU enters fail-safe mode, disabling the right airbag and side curtain airbag to prevent accidental deployment. Additionally, if the system identifies the short circuit as a continuous crash signal on certain models, it may trigger unintended airbag deployment. This fault constitutes a severe safety hazard and requires immediate repair.
B167011›
DTC B167011 indicates a short to ground in the Right Side Impact Sensor (RSIS) signal circuit. This sensor typically mounts on the right B-pillar, right front door, or right front side member to monitor acceleration changes during a side impact. The SRS control module logs this fault when it detects the sensor signal wire resistance to ground falls below the threshold (typically 0-5Ω). An insulation failure in the sensor circuit causes this fault. The control module receives a continuous 0V signal (ground potential), preventing it from correctly determining impact severity. This fault triggers fail-safe mode, disabling the right side airbag and side curtain airbag, and illuminates the instrument panel airbag warning light. It severely compromises occupant protection during a side impact and constitutes a high-risk safety fault.
B167100›
The Right Side Impact Sensor is a key safety component of the Supplemental Restraint System (SRS). The sensor typically mounts in the right B-pillar, right front door, or right C-pillar. It monitors acceleration changes on the right side of the vehicle. Upon detecting severe deceleration from a side impact, the sensor sends a crash signal to the SRS control unit to trigger the right side airbag and/or side curtain airbag deployment. DTC B167100 indicates the SRS control module fails to receive a valid signal from the Right Side Impact Sensor, or the received signal falls out of range (including open circuit, short circuit, signal distortion, or no sensor response). This fault disables the right side impact protection function. The airbags may fail to deploy during a side collision. The system illuminates the airbag warning light to alert the driver of a safety system fault.
B167200›
DTC B167200 indicates the airbag system (SRS) detects a mismatch between the configuration parameters of the Right Side Impact Sensor (typically mounted inside the right B-pillar) and the calibration data stored in the SRS control module. This is not a basic circuit continuity fault; it involves sensor ID recognition failure, hardware parameter verification errors, or lost/corrupted software configuration data. In the BYD architecture, this sensor monitors lateral acceleration changes and provides critical data for side airbag and side curtain airbag deployment decisions. This fault forces the SRS into a degraded mode. The right side airbag and side curtain airbag may fail to deploy during a collision. Additionally, the system may send an abnormal crash signal via a hardwired connection to the BMS and Vehicle Control Unit (VCU), triggering high-voltage system power cut-off protection or a reduced power mode.
B167300›
This fault code indicates a communication failure between the airbag control module (SRS ECU) and the right side impact sensor (SIS). On models such as the BYD Qin PRO, the right side impact sensor typically mounts inside the right front door trim panel, below the right B-pillar, or beside the right front seat. The sensor connects to the SRS ECU via a LIN bus or hardwire to monitor real-time lateral acceleration changes on the right side of the vehicle. The ECU triggers DTC B167300 if it fails to receive valid data frames from the sensor over several consecutive ignition cycles, detects a bus short or open circuit, or encounters a data checksum failure. This fault may prevent the right side airbags (curtain and seat side airbags) from deploying during a side impact. Consequently, the airbag warning lamp (SRS lamp) illuminates continuously, and the vehicle passive safety system enters degraded protection mode.
B167500›
DTC B167500 indicates a communication interruption or data anomaly between the Airbag Control Unit (ACU) and the Left Rear Side Impact Sensor (typically mounted in the left C-pillar, left rear door frame, or rear seat side panel area). This sensor communicates with the ACU via a LIN bus or dedicated CAN line to monitor collision acceleration at the left rear of the vehicle. The ACU sets this code when it fails to receive a valid data frame from the sensor within a set cycle (typically 100-500ms) or receives data with a checksum error. This safety-critical fault prevents the side curtain airbag (CAB) and left rear side airbag from triggering accurately during a side impact, or in extreme cases, causes unintended airbag deployment.
B1676-00›
DTC B1676-00 indicates the airbag control module (SRS ECU) detects a communication interruption or circuit fault in the Left Rear Side Impact Sensor (LR-SIS). The sensor typically mounts on the vehicle's left rear side panel, inside the C-pillar trim panel, or on the side of the rear seat to monitor collision acceleration at the left rear of the vehicle. The ECU sets this fault code when it detects an open circuit, a short circuit, or internal sensor resistance outside the calibrated range (typically 2.0–3.0 kΩ, depending on the vehicle model). This SRS communication link fault may prevent the side airbags and side curtain airbags from deploying correctly during a side impact. It can also force the entire airbag system into a degraded protection mode, severely compromising passive safety performance.
B1676›
DTC B1676 indicates the airbag control unit (SRS ECU) detected a communication loss or physical disconnection at the Left Rear Side Impact Sensor. Located in the left rear C-pillar or rear door frame area, this sensor monitors collision acceleration at the left rear of the vehicle. The SRS ECU stores this DTC if it fails to receive a sensor signal within a predetermined time or detects abnormal circuit resistance (open/short circuit). This fault forces the side airbag system (including the side curtain and/or rear seat side airbags) into a degraded mode. The airbags may fail to deploy during a left-side collision, severely compromising passive safety. Repair immediately.
B1677-00›
DTC B1677-00 on BYD new energy vehicles (including DM hybrid and EV models) is a manufacturer-defined fault code. It denotes a communication fault between the Battery Management System (BMS) and the Motor Control Unit (MCU/VTOG), or a High Voltage Interlock Loop (HVIL) fault, rather than an SRS airbag crash sensor fault. This fault indicates an open circuit, short circuit, or communication interruption in the high-voltage safety interlock loop. When the BMS detects a high-voltage safety risk, it triggers a protection mechanism and cuts off the high-voltage power supply, preventing the vehicle from powering on, driving, or charging. This fault involves high-voltage safety and requires immediate repair.
B1677›
DTC B1677 indicates a short to ground in the left rear side impact sensor (SIS) signal circuit. In the BYD SRS (Supplemental Restraint System) architecture, the left rear side impact sensor typically mounts below the B-pillar or near the left rear door frame to monitor collision acceleration at the left rear of the vehicle. When the sensor signal wire shorts to the vehicle body ground, the SRS control module (ACM) detects a signal voltage continuously below the threshold (usually <0.5V) and logs a short-to-ground fault. This fault disables the left rear side collision detection function, forces the system into fail-safe mode, and illuminates the instrument cluster SRS warning lamp. During a side collision, the left-side curtain airbag and seat side airbag may fail to deploy, posing a serious safety risk.
B167711›
B167711 is a BYD Supplemental Restraint System (SRS) diagnostic code indicating a short to ground in the left rear side impact sensor signal circuit. This sensor typically mounts in the left B-pillar or C-pillar area. It detects acceleration changes during a side impact and provides a collision severity signal to the Airbag Control Unit (ACU). A short to ground indicates insulation failure between the sensor signal wire (SIG) or power wire (VB) and the vehicle body ground (GND), dropping the resistance below the normal threshold (typically <5Ω). This fault prevents the ACU from receiving the collision signal, triggers the system fail-safe mechanism, disables deployment of the left rear side airbag and side curtain airbag, and illuminates the airbag warning light. During a severe collision, the affected airbags may fail to inflate, posing a severe safety hazard.
B167800›
This DTC indicates the SRS electronic control unit detects a functional fault in the Left Rear Side Impact Sensor (mounted in the lower left B-pillar or inside the left rear quarter panel). Specifically, the ECU receives no valid acceleration signal, the signal exceeds the normal threshold (typically 0.5-4.5V), or the system detects an open or short circuit. This sensor monitors side-impact acceleration on the left rear of the vehicle. The ECU uses this signal to determine whether to deploy the left curtain airbag and rear side airbag. When this fault occurs, the system enters fail-safe mode, illuminates the airbag warning light, and disables the related side airbags, significantly increasing the risk of occupant protection failure during a side collision.
B167900›
DTC B167900 indicates a logic error or communication protocol mismatch in the parameter data transmitted from the left rear side impact sensor (typically installed in the left C-pillar or rear door frame area) to the SRS airbag control unit. This is not a simple circuit fault (such as an open or short circuit). Instead, specific identification parameters uploaded by the sensor (such as part number ID, calibration zero offset value, sensitivity coefficient, or communication checksum) exceed the SRS ECU storage range or fail verification. Possible causes include: - Incorrect sensor configuration (e.g., failing to write parameters after accident repairs) - Corrupted parameter data stored in the sensor's internal ASIC chip - LIN/CAN bus communication interference causing data frame errors - Unstable sensor supply voltage causing abnormal analog-to-digital conversion This fault prevents the SRS system from confirming sensor data reliability. The system may enter a degraded mode, disabling window airbag or side curtain airbag deployment and significantly reducing side impact protection.
B167A-00›
DTC B167A-00 indicates the airbag control unit (SRS ECU/ACU) detects an open circuit, abnormal resistance, or complete loss of communication in the Right Rear Side Impact Sensor (RR-SIS) circuit. This sensor typically mounts in the right rear C-pillar, D-pillar, or inside the right rear quarter panel to monitor collision acceleration signals from the right rear of the vehicle. The ACU sets this DTC if it fails to receive a valid signal from the sensor within a predetermined time, or if it detects circuit resistance exceeding the threshold (typically >10kΩ or an open circuit). This fault forces the right side airbag system (side airbag/side curtain airbag) into fail-safe mode. The system may fail to deploy correctly during a side impact, severely compromising occupant protection. The front airbag system typically remains operational.
B167A›
DTC B167A indicates the SRS (Supplemental Restraint System) ECU detects a communication interruption or physical disconnection of the Right Rear Side Impact Sensor (SIS). This sensor mounts in the right C-pillar area or near the rear door frame to monitor collision acceleration signals from the right rear of the vehicle. The SRS ECU sets this DTC if it fails to receive a valid signal from the sensor within the specified detection period, or if it detects circuit resistance outside the calibrated range (open circuit ∞Ω or short circuit 0Ω). This safety-critical fault severely compromises rear occupant side-impact protection. During a right-side collision, it may cause the side and curtain airbags to fail to deploy or deploy with incorrect timing.
B167A00›
This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or open circuit at the Right Rear Side Impact Sensor. The sensor typically mounts in the right C-pillar, rear sill, or right rear door frame area to monitor acceleration changes during a right rear side impact. The ECU sets DTC B167A00 when it fails to receive the sensor signal or detects abnormal circuit resistance (open circuit). This fault disables the right rear side collision detection function. During a side impact, the system may fail to accurately determine collision severity, causing the side airbag and curtain airbag to fail to deploy or deploy at the incorrect time, severely compromising occupant safety.
B167B-00›
This DTC indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance connection (short to ground) between the right rear side impact sensor (SIS) signal circuit and body ground (GND). BYD SRS architecture typically uses piezoelectric or acceleration-type side impact sensors. These sensors mount inside the right rear door, behind the C-pillar trim panel, or beside the rear seat to monitor lateral impacts to the right rear of the vehicle. When the sensor signal wire shorts to ground, the ECU continuously receives a low-level signal near 0V and cannot correctly identify actual collision deceleration signals. This causes the following: 1) the right rear airbag (side airbag/curtain airbag) may fail to deploy during a side impact; 2) the system enters fail-safe mode, illuminates the airbag warning lamp, and may disable the entire airbag system. Cycling the ignition typically cannot clear this hard fault.
B167B›
DTC B167B indicates the Supplemental Restraint System (SRS) detects an unintended low-resistance connection (short to ground) between the Right Rear Side Impact Sensor signal circuit and vehicle ground (GND). This sensor typically mounts in the right C-pillar, rear rocker panel, or rear seat side panel area to monitor side-impact acceleration at the right rear of the vehicle. During a short to ground, the SRS control module detects an abnormal drop in sensor voltage (approaching 0V) and registers a sensor circuit fault. This fault forces the SRS into a degraded mode: the right side airbag and curtain airbag may fail to deploy during a collision, or the system may falsely trigger its fail-safe mechanism, keeping the airbag warning lamp illuminated and severely compromising passive safety.
B167B11›
DTC B167B11 has different definitions depending on the vehicle model. Early models, such as the BYD E2, E3, and Qin EV, define this fault as a short to ground in the right rear side impact sensor (SIS) signal circuit within the SRS airbag system. Newer models, such as the Han EV, define it as a short to ground in the left front seat heater circuit. Regardless of the application, sub-code '11' indicates a short to ground. For the SRS system, this fault indicates the airbag control unit (ACU) continuously detects 0V on the right rear side impact sensor signal wire (below the 0.3V threshold), preventing the ACU from receiving the correct collision acceleration signal. This triggers the SRS fail-safe mode, constituting a serious safety hazard. The fault may prevent the side airbag or side curtain from deploying correctly during a side impact, or falsely trigger the airbag warning lamp while driving. For the seat heater definition, this fault indicates the heating element circuit current increased abnormally, causing the control module to activate overcurrent protection.
B167C00›
DTC B167C00 indicates the Right Rear Side Impact Sensor in the Supplemental Restraint System (SRS) detects an internal functional fault. The sensor typically mounts in the vehicle C-pillar or right rear quarter panel area to monitor collision acceleration on the right rear side. The SRS control module sets this fault code when the sensor experiences an internal circuit fault, communication interruption, or abnormal signal. This fault may prevent the right rear side airbag or curtain airbag from deploying normally during a side impact, severely compromising passive safety performance. It does not directly affect normal vehicle driving functions.
B167D00›
This DTC indicates the internal parameters of the right rear side impact sensor (typically located in the right C-pillar or rear door frame area for side impact detection) exceed the normal tolerance range or fail validation. Unlike a simple communication error, this fault confirms a normal communication link between the sensor and the SRS control module. However, the sensor detected abnormal internal calibration data, sensitivity parameters, or zero-point offset during self-check. Potential causes include corrupted internal sensor EEPROM data, physical characteristic drift from long-term use, A/D conversion errors resulting from unstable supply voltage, or internal accelerometer reference shift due to sensor installation stress deformation. This fault prevents the SRS system from accurately determining right-side impact severity. It may delay or incorrectly trigger the side airbag or side curtain airbag, severely compromising passive safety performance. The system typically defaults to a degraded protection mode.
B167E00›
This DTC indicates interrupted data communication between the Airbag Control Unit (ACU) and the right rear Side Impact Sensor (SIS). The sensor typically mounts inside the right rear door trim panel or below the C-pillar and connects to the ACU via a LIN bus or hardwire connection. The fault occurs when the ACU fails to receive a valid data frame from the sensor within the specified time window (typically 100-500ms) or receives incorrect checksum data. Consequently, the ACU cannot obtain real-time collision acceleration data from the vehicle's right rear, directly affecting the deployment logic for the side and curtain airbags. The system enters fail-safe mode, illuminates the airbag warning lamp, and may disable the right-side airbag circuit. This condition can prevent proper airbag deployment during a side collision, posing a severe safety risk.
B1680-00›
DTC B1680-00 indicates the SRS (Supplemental Restraint System) control module detected an open circuit in the Passenger Airbag Cutoff Switch or its related wiring. This switch, typically located in the center console or glovebox area, manually disables the airbag when a child seat occupies the front passenger seat. The fault occurs because the SRS ECU fails to detect a valid resistance signal from the switch during the self-check cycle (normally a specific resistance range, such as 2-5kΩ, or a ground signal), triggering a level-two safety warning. This condition may forcibly disable the front passenger airbag or place it in an uncertain state, severely compromising the occupant protection strategy during a collision. The fault also illuminates the SRS warning light on the instrument cluster and prevents the vehicle from passing a safety inspection.
B1680›
This DTC indicates the airbag control unit (SRS ECU) detects a communication loss or abnormal signal from the passenger airbag cutoff switch (PAD switch). Typically located on the right side of the center console or inside the glovebox, this switch manually controls the front passenger airbag activation/deactivation status (e.g., when installing a child safety seat). The ECU triggers DTC B1680 if it fails to detect a valid resistance signal within a set cycle (normal operation uses different resistance values to distinguish ON/OFF positions, such as 2.2kΩ/4.7kΩ) or detects an open circuit (infinite resistance). This fault causes: 1) the front passenger airbag status to enter an unknown mode, where the system may default to disabling the airbag to prevent unintended deployment, reducing crash protection; 2) the instrument panel airbag warning light to illuminate continuously; 3) some models to record abnormal crash event readiness data, affecting accident liability determination.
B168000›
DTC B168000 indicates the SRS (Supplemental Restraint System) control module detected a communication interruption or physical disconnection between the Passenger Airbag Disable (PAD) switch and the main control unit. The PAD switch typically mounts in the center console or near the glovebox to manually disable the front passenger airbag (e.g., when installing a child safety seat). The SRS module triggers this fault code if it fails to receive the switch resistance signal (typically a specific resistance range, such as 2kΩ-5kΩ indicating different states) within a predetermined time, or if it detects an open circuit (infinite resistance). This fault forces the front passenger airbag system into fail-safe mode and continuously illuminates the instrument cluster airbag warning lamp. During a collision, the front passenger airbag may fail to deploy or exhibit unpredictable behavior, severely compromising passive safety.
B1681-00›
On BYD vehicles, B1681-00 typically indicates an immobilizer authentication failure or communication fault between the Body Control Module (BCM), the smart key, and the immobilizer reader coil (antenna). This fault prevents the BCM from verifying key validity, triggering the anti-theft lockout. Symptoms include failure to start, failure to engage high-voltage power (OK mode), or the instrument cluster displaying "Please check the starting system". Although some documents describe this code as an airbag switch short to ground, repair experience and fault code definitions confirm it primarily points to an interrupted immobilizer authentication process involving the low-frequency antenna, immobilizer coil, or a BCM software or hardware fault.
B1681›
DTC B1681 indicates the Passive Anti-Theft System (PATS) transceiver module fails to receive a valid signal or cannot establish normal communication with the engine control module (PCM/ECM). This fault belongs to the Body Security system, not the SRS airbag system (Note: original documentation may misclassify the airbag switch). The fault triggers the vehicle anti-theft immobilizer, preventing the engine from starting (No Crank/No Start). The instrument cluster Security Light typically flashes rapidly. The fault stems from abnormalities in key transponder recognition, 125kHz radio frequency signal transmission at the transceiver coil, or data exchange on the dedicated communication line between the PATS module and the PCM. Consequently, the PCM cannot verify key validity and inhibits engine starting.
B168111›
DTC B168111 indicates the front passenger Occupant Classification System (OCS) detects a short to ground or abnormal signal. The system uses pressure or capacitive sensors integrated into the seat to monitor passenger occupancy status and weight data to control the passenger airbag deployment strategy. When the system detects a sensor circuit short to ground, internal sensor damage, or an abnormal signal, it logs this DTC and illuminates the airbag warning light. Under these conditions, the passenger airbag may enter fail-safe mode (forced off or deployed based on the worst-case scenario) and fail to provide effective protection during a collision. This is a severe safety fault.
B1684-00›
DTC B1684-00 indicates a functional fault in the Occupant Classification System (OCS). The OCS is a key subsystem of the Supplemental Restraint System (SRS). Located inside the front passenger seat, the system uses a pressure sensing mat and an electronic control module to monitor the seat load status in real time (empty seat/child/adult). It sends classification signals to the SRS ECU to determine the front passenger airbag deployment strategy during a collision (deployment decision, force, and timing). This DTC triggers when the OCS and SRS ECU lose communication, a sensor signal exceeds its threshold, the system loses calibration data, or a hardware failure occurs. This fault forces the airbag system into fail-safe mode. During a collision, this condition may cause unintended airbag deployment (injuring a child) or failure to deploy (loss of protection). This poses a serious safety risk and requires immediate repair.
B1684›
In BYD vehicles, DTC B1684 indicates an Occupant Classification System (OCS) fault. The OCS mounts inside the front passenger seat and consists of the OCS control module and pressure sensors. The system detects pressure distribution and weight on the seat surface to identify the front passenger seat status (empty/child/adult). It sends occupant presence and type signals to the airbag control unit (SRS ECU). The SRS ECU uses these signals to determine the front passenger airbag deployment strategy (whether to deploy and deployment force) during a collision. When the SRS ECU detects a communication loss with the OCS module, an abnormal sensor signal, or missing system calibration data, it logs DTC B1684-00, illuminates the airbag warning light, and enters fail-safe mode (typically disabling front passenger airbag deployment). Consequently, the system may fail to protect the front passenger effectively during a collision, or it may deploy accidentally when no one occupies the seat, causing secondary injury.
B168400›
DTC B168400 indicates the Occupant Classification System (OCS) detects an internal fault or abnormal signal. Installed inside the front passenger seat, this key subsystem of the SRS airbag system uses a pressure sensor matrix to monitor seat occupancy status in real time (empty seat/child/adult). The OCS controls the front passenger airbag deployment strategy (suppression, low-power deployment, or full-power deployment) based on the occupant weight class (usually Class 0, Class 1, Class 2, or Class 3). When this DTC triggers, the SRS ECU cannot accurately determine the front passenger occupant status. The system enters fail-safe mode, disables the front passenger airbag by default (to prevent injury to children), and illuminates the airbag fault warning lamp. This fault may prevent correct front passenger airbag deployment during a collision or cause unintended deployment when the seat is empty, severely compromising passive safety performance.
B168500›
DTC B168500 indicates an invalid configuration fault in A/C System Circuit 1 (specifically the electric compressor drive circuit). On BYD Qin PRO models, 'Circuit 1' typically refers to the electric A/C compressor high-voltage drive and LIN communication circuits. 'Invalid configuration' indicates mismatched communication parameters between the HVAC ECU and the compressor control unit, an unconfigured LIN address, or abnormal circuit topology recognition. This fault completely disables the A/C cooling function and may limit vehicle power output. Although some sources classify this as an SRS fault, the BYD fault code structure (B16xxxx) categorizes it under the body HVAC system, with no direct relation to the airbags.
B168600›
DTC B168600 indicates the SRS (Supplemental Restraint System/airbag) control module detects an abnormal configuration status in "Circuit 2" (typically the front passenger-side airbag deployment circuit). In the BYD Qin PRO airbag architecture, the control module determines system status by monitoring circuit resistance (standard value 2.0–3.0 Ω) and configuration data. "Invalid configuration" means the control module reads a circuit resistance outside the threshold (open circuit >10 Ω or short circuit <1 Ω), or detects circuit configuration data that does not match the vehicle VIN or lacks correct coding. This fault may prevent the passenger-side airbag from deploying properly during a collision. The system also illuminates the instrument cluster airbag warning light and may disable the entire airbag system to enter fail-safe mode.
B168700›
DTC B168700 indicates the Airbag Control Module (SRS ECU) detects that the configuration parameters for Ignition Circuit 3 (typically the left front seat belt pretensioner or left side airbag deployment circuit) do not match the actual vehicle configuration. Specifically, the airbag type, resistance range, or circuit topology data stored in the control module does not match the installed hardware, preventing the system from validating the circuit. This fault prevents the safety device corresponding to Circuit 3 from deploying during a collision, creating a severe safety hazard that requires immediate repair. Common causes include failing to complete online programming after replacing the SRS control module, installing non-genuine parts with different resistance characteristics, or modifying or damaging the wiring harness, which alters the circuit's electrical properties.
B168800›
DTC B168800 indicates the SRS (Supplemental Restraint System) control unit detects invalid configuration parameters in circuit 4 (typically the driver-side seat belt pretensioner circuit). Specifically, the control unit detects the circuit resistance falls outside the standard range (normally 2-3 ohms), or the identified hardware configuration does not match the software calibration. This constitutes a hard fault in the passive safety system. During a collision, the corresponding restraint device (seat belt pretensioner or airbag) may fail to deploy, severely compromising occupant protection. Upon fault detection, the SRS control unit illuminates the instrument cluster airbag warning light and may disable the entire airbag system.
B168900›
DTC B168900 indicates the SRS (Supplemental Restraint System) control module detects invalid configuration data for deployment loop 5 (typically the right front seat side airbag or right curtain airbag, depending on vehicle trim level). This constitutes a Configuration Error rather than a simple open or short circuit. The electrical characteristics of this loop (e.g., igniter resistance, loop integrity detection parameters) do not match the calibration data stored in the ECU. Possible causes include: loop resistance outside the threshold (>5Ω or <1Ω), incorrect ECU coding, failure to write configuration data after replacing the airbag module, crash data corruption, or a software version mismatch. This fault may prevent the specific airbag from deploying during a collision and illuminates the airbag warning light.
B168A00›
DTC B168A00 indicates the Airbag Control Unit (ACU) detects the configuration parameters for Circuit 6 (typically the right side airbag/side curtain or right rear side airbag ignition circuit) do not match the system calibration data. This is an SRS configuration fault, not a simple open or short circuit. "Invalid configuration" means the control unit's internal algorithm detects the circuit's electrical characteristics (such as squib resistance, capacitance, or internal ECU configuration code) differ from the vehicle factory settings or current hardware configuration. This condition can prevent the airbag from deploying correctly or cause unintended deployment during a collision, constituting a Level 2 safety fault.
B168B00›
DTC B168B00 indicates the SRS (airbag system) control module detects invalid configuration parameters for Airbag Loop 7. In the BYD Qin PRO SRS architecture, Loop 7 typically corresponds to the right front seat side airbag or the right rear side curtain module. During self-diagnosis, the SRS control module detects that the loop's electrical impedance, squib resistance, or configuration coding does not match the calibrated value (typically 2.0-3.0Ω), or the configuration data stored in the module's internal EEPROM is corrupted or missing. This is a configuration validity fault rather than a simple open or short circuit. This fault can prevent the corresponding airbag from deploying during a collision, illuminates the airbag warning lamp continuously, and forces the system into fail-safe mode.
B168C00›
DTC B168C00 indicates the airbag control unit (SRS ECU) detects an invalid or missing configuration parameter for Trigger Circuit 8 (Loop 8). In the BYD Qin PRO SRS architecture, Loop 8 typically corresponds to the driver-side airbag ignition circuit or the front passenger-side pretensioner circuit. This is a Configuration Fault, not a hardware short or open circuit. The ECU recognizes the loop hardware, but the internally stored configuration data (such as resistance thresholds, ignition characteristic curves, and installation position coding) mismatches the actual vehicle, or the ECU programming table does not activate the loop. This fault disables the safety function of the affected loop, but typically does not affect the protective functions of other correctly configured loops.
B168D00›
DTC B168D00 indicates the Airbag Control Unit (ACU) detects invalid configuration data for Ignition Loop 9. In the BYD Qin PRO SRS system, Loop 9 typically corresponds to the front passenger knee airbag or rear seat side airbag circuit, depending on the vehicle configuration level. "Invalid configuration" means the "configuration present flag", "rated resistance parameter", or "capacity type" in the ACU EEPROM data does not match the installed hardware. This condition also occurs if the ACU detects a load on a circuit marked "not installed", or detects an open circuit on a loop marked "installed". This fault causes the ACU to enter degraded mode. During a collision, the ACU may fail to deploy the airbag on this circuit, or it may trigger a fail-safe strategy that restricts overall SRS functionality.
B168E00›
DTC B168E00 indicates an invalid configuration in Ignition Loop 10 of the Supplemental Restraint System (SRS). On the BYD Qin PRO, Loop 10 typically corresponds to the ignition circuit for the right seat belt pretensioner or the right side curtain airbag. "Invalid configuration" means the SRS control unit detects a circuit resistance outside the standard range (2.0-3.0Ω), or the stored configuration data does not match the installed hardware. This fault prevents the corresponding airbag or pretensioner from deploying normally during a collision. The system also illuminates the airbag warning lamp and may disable the entire SRS, severely impacting passive safety performance.
B168F00›
DTC B168F00 indicates the Airbag Control Unit (ACU) detects the configuration data for ignition circuit 11 (typically the driver-side seat side airbag or left seat belt pretensioner circuit) does not match the actual vehicle configuration. On the BYD Qin PRO, circuit 11 typically corresponds to the side airbag module built into the driver seat. This fault occurs when configuration parameters stored in the ACU (such as airbag resistance threshold, serial number, and installation status) do not match the actual detected circuit characteristics. This mismatch can prevent the airbag from deploying properly during a collision or trigger the system to enter a safety downgrade mode (cutting power to the circuit). Common causes include replacing the seat assembly, ACU, or wiring harness without performing online configuration (Coding), or a loose wiring harness connector under the seat preventing the ACU from correctly identifying the airbag module.
B169000›
DTC B169000 indicates the airbag control unit (SRS ECU) detects an abnormal configuration parameter in Loop 12. In the BYD Qin PRO SRS system, "Loop 12" typically corresponds to the communication/ignition circuit for the left front seat side airbag (or seat occupancy recognition sensor). "Invalid configuration" means the configuration data stored in the ECU does not match the connected hardware. Causes include circuit resistance outside the standard range (normal: 2.0-3.0 Ω), wiring open or short circuits, or failing to write the configuration after replacing the airbag assembly or control unit. This fault may prevent the corresponding airbag from deploying properly during a collision or create an unintended deployment risk, classifying it as a functional safety fault.
B1691-00›
B1691-00 (Factory Encrypted) is a safety configuration fault code for the BYD SRS (Supplemental Restraint System). It indicates an error in the unique encrypted configuration data stored within the airbag ECU (Electronic Control Unit) and bound to the vehicle VIN. This fault indicates the ECU detected missing, corrupted, or mismatched internal safety configuration data, triggering the system safety lock mechanism. In this state, the airbag system disables deployment to prevent accidental deployment or failure caused by an unauthorized ECU, incorrect configuration, or data corruption. This condition severely compromises the vehicle's passive safety performance. Reconfigure the system using the manufacturer's dedicated diagnostic equipment.
B1691›
DTC B1691 indicates the Airbag Control Module (ACM) detects a verification failure of its internally stored factory-encrypted data or security authentication key. This fault involves the SRS security authentication mechanism. The module triggers this fault when its stored factory configuration data, encryption key, or anti-theft authentication information does not match the reference data stored in the VCU/BCM. Common causes include: installing a non-genuine airbag module without online matching, corrupted internal EEPROM data, vehicle power system anomalies causing encrypted data loss, or failing to complete the module matching procedure correctly during production or repair. This safety-related fault causes the airbag system to enter a degraded mode and may limit normal airbag deployment.
B169100›
DTC B169100 indicates the Supplemental Restraint System (SRS) is in "Factory Lock" mode. BYD uses this protective locking mechanism during production, transport, or after SRS control module replacement. This state forces the Airbag Control Unit (ACU) into factory test mode and electrically disables all airbags, side curtain airbags, and seat belt pretensioners. These components will not deploy even in a severe collision. This status is a software configuration issue, not a hardware fault. It continuously illuminates the airbag warning light and completely disables the vehicle's passive safety functions. Resolve this condition immediately.
B1693-00›
DTC B1693-00 indicates high resistance or an intermittent open circuit in the Supplemental Restraint System (SRS) Electronic Control Unit (ECU) ground circuit. Specifically, the resistance of the ground path from the SRS ECU through connector G36 (specifically terminal G36-35) to the main body ground point exceeds the calibrated threshold (normally less than 1Ω). This fault causes an unstable ECU power supply reference potential, triggers a system self-check failure, and continuously illuminates the airbag warning lamp (SRS lamp). In extreme cases, this condition prevents airbag deployment during a collision or causes unintended deployment, severely compromising passive safety system functionality.
B1693›
The BYD SRS (Supplemental Restraint System) strictly defines DTC B1693 as "Driver Airbag Circuit Resistance Low/Short to Ground", not a simple ground connection issue. This fault indicates the airbag control unit (ACU) detects the driver-side airbag (steering wheel airbag) firing circuit resistance is below the standard threshold (normal range 2.0–3.0 Ω; values below 1.5 Ω trigger this code). Potential causes include an internal short circuit in the steering wheel clock spring flexible printed circuit, abnormal contact resistance at the airbag connector, damaged wiring harness insulation causing a short to ground, or a faulty ACU internal firing driver circuit. This fault prevents airbag deployment during a collision (open-circuit condition) or causes unintentional deployment without a collision (short-circuit condition), representing a critical safety function failure.
B1694-00›
The SRS (airbag system) control unit records DTC B1694-00 when it detects its operating supply voltage falls below the calibrated threshold (typically 9.0V-10.5V, depending on specific vehicle calibration). This fault indicates a voltage drop in the airbag ECU constant power or IGN supply circuit, which may prevent the airbag system from deploying properly during a collision or cause unintentional deployment while driving. This fault triggers a safety system degraded mode. The ECU illuminates the airbag fault warning lamp and stores the fault code. On some models, this condition also limits functions such as the seat belt pretensioners and airbag backup power supply.
B1697-00›
DTC B1697-00 indicates the airbag control unit (SRS ECU) internal self-test detected a critical function fault. The ECU integrates the acceleration sensor, safing sensor, firing decision logic, and diagnostic communication module. Potential root causes include: 1) Data verification failure in the ECU internal microprocessor or memory (EEPROM/Flash); 2) Abnormal output from the power management module (12V-5V/3.3V voltage regulator circuit); 3) The crash detection algorithm continuously detecting an internal logic conflict; 4) Communication interface circuit fault with the crash sensors (front door, side airbag, center sensor). This fault causes the ECU to enter a degraded mode, disabling deployment of the airbags, seat belt pretensioners, and pedestrian protection devices. In extreme cases, it may cause unintended airbag deployment or failure to deploy during a collision. This is a safety-critical fault.
B1694›
DTC B1694 indicates the airbag control unit (SRS ECU) detects its operating supply voltage is below the system threshold (usually 9.0V-9.5V, depending on vehicle calibration). The SRS system uses a dual power supply design: constant power (+B, memory power) and ignition switch power (IG). This ensures airbag deployment during a collision even if the ignition switch is off. Low voltage prevents normal operation of the airbags, seat belt pretensioners, crash sensors, and CAN communication. The system enters fail-safe mode (the instrument cluster airbag warning light remains illuminated). In extreme cases, this causes deployment failure during a collision or risks unintended deployment. New energy vehicles use a DC-DC converter instead of a traditional alternator for low-voltage charging. Abnormal DC-DC output or high-voltage system power loss also triggers this code.
B169416›
DTC B169416 indicates the airbag control unit (SRS ECU) detects an internal operating voltage below the calibrated threshold (typically below 9V), or a functional fault in the ECU internal power management module or voltage regulation circuit. This hardware-level fault indicates the SRS ECU cannot maintain the stable operating voltage required for its internal microprocessor, acceleration sensor, and ignition circuit. When triggered, the ECU enters fail-safe mode. This condition can cause complete airbag system failure (airbags fail to deploy during a collision), prevent seat belt pretensioner activation, or generate a false alarm resulting in unintended airbag deployment. This fault poses a severe safety risk and requires immediate repair.
B1695-00›
DTC B1695-00 indicates the airbag control unit (SRS ECU) detected its operating supply voltage exceeds the system safety threshold (typically >16V). On BYD new energy vehicles, this fault means the 12V low-voltage system supply voltage rose abnormally, exceeding the tolerance range of the SRS ECU internal circuits. The SRS system is highly sensitive to voltage. Excessive voltage can cause reference voltage drift in the internal A/D converter, capacitor breakdown, or unintended airbag deployment. As a safety mechanism, the ECU illuminates the airbag warning lamp, stores the fault code, and enters a fail-safe mode. This mode disables the airbags and seat belt pretensioners, preventing abnormal voltage from causing unintended deployment or failure during a collision.
B1695›
In the BYD SRS (airbag) system, DTC B1695 indicates a front passenger Occupant Classification System (OCS) fault, rather than the literal "power supply voltage too high". This DTC indicates the SRS ECU detected an abnormal front passenger seat occupancy sensor signal, a communication interruption, or calibration data outside the valid range. The OCS uses a piezoelectric sensor mat to detect front passenger seat occupancy and occupant weight category to control airbag deployment and staged inflation force. If sensor resistance drifts, signal voltage is abnormal (standard no-load value is 1.2-1.5V), the communication circuit opens, or system calibration is incorrect, the SRS ECU triggers DTC B1695 and illuminates the airbag warning lamp. This creates a serious safety risk, as the front passenger airbag may deploy incorrectly or fail to deploy during a collision.
B169517›
DTC B169517 indicates the airbag control unit (SRS ECU/ACU) detected an anomaly during internal self-check, usually pointing to a fault in the ECU internal processor, memory, or power management module. In the BYD diagnostic protocol, sub-code '17' specifically indicates an internal ECU circuit fault or a logic error resulting from supply voltage exceeding the threshold. When the SRS ECU detects an internal oscillator fault, EEPROM data checksum failure, ADC conversion error, or watchdog reset, it sets this code and enters degraded mode. This mode may disable some or all airbag deployment functions. Because the ECU is the core of the passive safety system, this fault presents a severe safety risk and can prevent normal airbag deployment during a collision.
B1696-00›
DTC B1696-00 indicates an internal hardware or software fault in the airbag electronic control unit (SRS ECU). This fault points to an abnormality in the ECU internal microprocessor, memory (EEPROM), power management module, or internal communication bus, preventing the ECU from completing self-checks or running safety algorithms normally. This fault is a current hard fault (Present DTC), meaning the ECU has detected substantial internal damage and cannot perform normal crash detection and airbag deployment decision functions. While the fault is present, the airbag system may enter fail-safe mode (fully disabled or partially restricted). In a collision, the airbags may fail to deploy properly, creating a severe safety hazard. This fault differs from external wiring or sensor faults; repairing the wiring harness will not resolve it.
B1696›
For the BYD SRS (Supplemental Restraint System/airbag system), DTC B1696 indicates a fault in the Seat Occupancy Sensor or its related circuit, not hardware damage to the SRS ECU itself. This sensor mounts inside or underneath the driver or front passenger seat. It detects seat occupancy and classifies occupant weight, serving as a key input signal for the airbag deployment logic. When the ECU detects an open circuit, short circuit, abnormal signal, or communication failure in the sensor circuit, it illuminates the airbag warning lamp. The system may default to disabling the corresponding airbag and illuminate the 'airbag off' indicator. This severely compromises occupant protection during a collision. On some models, failing to perform the online configuration learning procedure after replacing the seat or sensor also triggers this code.
B1697›
DTC B1697 indicates the airbag control unit (SRS ECU) detected an internal hardware fault or critical support circuit error, forcing the system into fail-safe mode. This fault involves an internal microprocessor calculation error, EEPROM data corruption, an abnormal internal accelerometer signal, an ignition driver circuit fault, or a severe fault in the external power supply, ground, or communication lines. When triggered, the SRS ECU disables deployment of all airbags and seat belt pretensioners. The vehicle provides no passive safety protection during a collision. This severe fault compromises driving safety.
B169700›
This DTC has two definitions across different BYD vehicle platforms: 1) In early models such as the E2, E3, and Qin EV, it indicates an internal fault in the SRS_ECU (airbag control unit) involving communication, power supply, or internal circuit failures in the main safety system control module, potentially affecting crash protection functions. 2) In models equipped with seat memory such as the Song MAX, Song Pro, Tang, and Song PLUS, repair databases indicate this DTC usually flags a Driver Seat Position Memory - Store 1 Malfunction. This involves Seat Control Module (SCM) storage or recall failures for memory position 1, or distorted signals from related position sensors (fore-aft/height/tilt). In either case, the control module detects abnormal internal storage, a communication timeout, or actuator feedback signals exceeding the threshold. Confirm the fault subtype using the VDS diagnostic tool based on the specific vehicle model.
B1698-00›
B1698-00 indicates the airbag system electronic control unit (SRS ECU) detects an internal fault or critical function abnormality. This fault code typically indicates an SRS ECU internal memory error, processor fault, power supply voltage out of operating range (overvoltage or undervoltage), or a persistent communication bus fault between the ECU and the crash sensors or airbag modules. In BYD Qin series vehicles, this fault forces the airbag system into fail-safe mode and continuously illuminates the instrument panel airbag warning lamp. During a collision, the vehicle may fail to deploy the airbags and seat belt pretensioners, posing a severe safety hazard. This fault code is a hard fault that does not clear automatically and requires professional diagnosis and repair.
B1698›
DTC B1698 indicates the airbag system electronic control unit (ACU/SRS ECU) detects an internal system fault or critical function failure. This fault involves an ECU internal processor self-check anomaly, memory data checksum error, power supply monitoring circuit fault, firing circuit diagnostic system anomaly, or interrupted communication with the vehicle CAN network. As the core control module of the passive safety system, the SRS ECU monitors crash sensor signals in real time and controls the firing circuits for multiple airbags and seat belt pretensioners. When B1698 triggers, the system typically enters fail-safe mode and automatically disables all airbag and pretensioner deployment. This causes a complete loss of vehicle crash protection capability and poses a severe safety hazard.
B169800›
DTC B169800 indicates an internal fault or communication failure in the airbag control unit (SRS ECU). As the core control module of the airbag system, the SRS ECU monitors crash sensor signals, processes crash algorithms, and controls airbag and seat belt pretensioner deployment. This DTC indicates the ECU self-check detected an internal processor fault, memory error, power supply fault, or CAN communication interruption with other modules (such as the Vehicle Control Unit or Body Control Module). This fault poses a severe safety risk and may cause the airbags to fail to deploy or to deploy inadvertently during a collision. Repair immediately.
B1699-00›
B1699-00 indicates an internal hardware or basic software fault in the airbag electronic control unit (SRS ECU). This ECU integrates a central acceleration sensor, a crash detection algorithm processor, ignition driver circuits, and an energy storage capacitor. The following conditions trigger the DTC: abnormal ECU supply voltage (below 9V or above 16V for longer than the set time), internal memory (EEPROM/Flash) checksum failure, main control chip (MCU) watchdog reset, acceleration sensor self-test failure, or CAN communication controller fault. This is a hard fault. The ECU enters fail-safe mode and disables all airbag ignition circuits, preventing the airbags and seat belt pretensioners from deploying during a collision and posing a severe safety hazard.
B1699›
DTC B1699 indicates an internal self-check fault in the airbag system Electronic Control Unit (SRS ECU). As the core control module of the passive safety system, the SRS ECU integrates acceleration sensors, safing sensors, ignition driver circuits, and a microprocessor. This DTC triggers when the ECU detects an internal processor fault, memory data checksum error, internal communication bus anomaly, or power management module fault during the self-check. The airbag system enters fail-safe mode, meaning the airbags and seat belt pretensioners may fail to deploy during a collision. The instrument panel SRS warning light illuminates continuously. External power supply or ground faults typically trigger specific DTCs such as B1693 (poor ground) and B1694/B1695 (abnormal supply voltage). DTC B1699 specifically indicates an internal circuit fault within the ECU itself.
B169A-00›
B169A-00 indicates an internal fault in the airbag control unit (SRS ECU) or a system-level communication fault. The SRS ECU is the core control module of the vehicle’s passive safety system, responsible for monitoring crash sensors, controlling airbag deployment, triggering seat belt pretensioners, and recording crash data. This fault code indicates the ECU self-check detected an internal processor fault, memory checksum failure, internal bus communication interruption, or critical circuit abnormality. This fault constitutes a serious safety hazard; it may prevent the airbag system from deploying correctly during a collision or cause unintended deployment. In BYD Qin series vehicles, the SRS ECU typically mounts beneath the center console or in the central armrest area, communicating with the vehicle network via the CAN bus.
B169A›
DTC B169A indicates the airbag control unit (SRS ECU) detects an internal system fault or critical function failure. This fault code typically indicates an abnormality in the ECU internal processor, memory, or power management module, forcing the airbag system into a degraded mode or complete failure state. Specific symptoms include crash detection algorithm failure, ignition loop driver circuit faults, or interrupted communication with other safety modules (such as seatbelt pretensioners and crash sensors). This fault directly prevents airbag deployment during a collision, disables seatbelt pretensioners, and continuously illuminates the instrument cluster airbag warning light. On some models, this fault restricts Child Presence Detection (CPD) and smart key system functions, as these systems share sensor data or communication buses.
B169B-00›
DTC B169B-00 indicates an internal self-diagnostic fault or severe communication error within the airbag control unit (SRS ECU). This fault indicates the microprocessor, memory (EEPROM/Flash), power supply monitoring circuit, or watchdog circuit within the SRS ECU detected an abnormality, preventing guaranteed airbag deployment. When this fault occurs, the SRS ECU enters fail-safe mode, illuminates the airbag warning light, and disables all airbags, seat belt pretensioners, and crash unlock functions, severely compromising passive safety. This is a Hard Fault; disconnecting the power typically will not clear it. Repair the power supply or communication wiring, or replace the ECU.
B169B›
DTC B169B (usually with sub-code -00) indicates a range/performance fault or invalid signal in the driver seat horizontal position sensor (DSeat Horizontal Position Sensor) circuit. This three-wire sensor (5V reference supply, signal ground, analog signal output) mounts on the driver seat slide rail to monitor the fore-and-aft seat position in real time (0-240 mm travel range). The BCM or seat control module sets this DTC when it detects the sensor output voltage falls outside the calibrated range (normally 0.5-4.5V, changing linearly with position), an open or short circuit, or a value that remains unchanged for an extended period. This fault directly affects the seat memory and welcome seat rearward movement functions. It may also prevent the airbag system from optimizing pretensioner force based on seat position (linked with the SRS on some models). This fault compromises user experience and vehicle safety.
B169C›
DTC B169C indicates the airbag control unit (SRS ECU) detects a critical internal function failure or self-diagnostic abnormality. This typically involves an ECU internal processor (MCU) calculation error, a non-volatile memory (EEPROM/Flash) data verification failure, abnormal power management module (PMIC) output, or the safety monitoring circuit (Watchdog) triggering a reset. As the core of the passive safety system, the SRS ECU receives crash sensor signals, determines collision severity, and triggers airbag deployment and seat belt pretensioners. This fault means the ECU cannot guarantee a normal response during a collision, potentially causing the airbags to fail to deploy or deploy unintentionally. This constitutes an Automotive Safety Integrity Level (ASIL) D functional safety fault.
B169C00›
DTC B169C00 indicates the airbag control unit (SRS ECU) detected a severe fault during its internal self-check. This typically involves an ECU internal memory (EEPROM/Flash) data checksum failure, a main processor (MCU) calculation error, or an internal power supply/clock circuit fault. This is a hard fault; the ECU cannot guarantee correct deployment of the airbags, seat belt pretensioners, and high-voltage interlock cut-off function during a collision. Upon triggering, the SRS ECU enters fail-safe mode, illuminates the instrument cluster airbag warning light, and disables the entire airbag system. Although the vehicle remains drivable, crash protection functions fail completely, posing a major safety risk.
B169D-00›
DTC B169D-00 indicates the airbag control unit (SRS ECU) detects an internal fault or abnormal system communication. This ECU is the core control module of the airbag system. It monitors crash sensor signals, determines crash severity, controls the deployment timing of the airbags and pretensioners, and records crash data (EDR). Faults in the ECU internal processor, memory, or power management circuit, interrupted communication with the vehicle CAN network, or data checksum errors trigger this fault code. This fault may cause the airbag system to enter fail-safe mode, preventing normal airbag deployment during a collision and severely compromising occupant passive safety protection. This is a critical safety-related fault.
B169D›
DTC B169D indicates the SRS (Supplemental Restraint System) ECU (Electronic Control Unit) detected a critical fault during its internal self-check. Specifically, this code indicates the airbag control module's internal monitoring circuit detected a processor fault, memory checksum error, power management circuit abnormality, or safety watchdog timeout. As the core of the passive safety system, the SRS ECU monitors crash sensor data in real time, diagnoses system integrity, and precisely controls the deployment timing of the airbags, seat belt pretensioners, and active head restraints during a collision. When B169D sets, the ECU cannot guarantee its decision-making logic reliability. It enters fail-safe mode and disables all airbag deployment functions. As a result, the airbags may fail to deploy during a frontal, side, or rear-end collision, and the instrument cluster airbag warning light remains illuminated. Although the vehicle remains drivable, the significantly reduced passive safety protection creates a serious safety risk.
B169D00›
DTC B169D00 indicates the airbag control unit (SRS ECU/ACU) detects an internal systemic fault. The ECU sets this code when it detects an abnormality in the processor core, non-volatile memory (NVM), safety sensor interface, or internal communication bus during the Power-on Self Test or cyclic monitoring. As the core controller of the passive safety system, the SRS ECU monitors crash acceleration sensor signals in real time, processes crash algorithm decisions, and controls the firing circuits for the airbag modules and seat belt pretensioners. This fault causes the ECU to enter Limp Home mode or fail completely. Consequently, the ECU cannot correctly determine crash severity or trigger the corresponding protective devices during a collision, leading to airbags failing to deploy or deploying unintentionally. This is an ASIL-D safety-critical fault. Potential causes include ECU hardware damage, software runaway, abnormal supply voltage (below 9V or above 16V lasting beyond the set threshold), CAN/LIN communication physical layer faults, or system lockout resulting from a short or open circuit in the external crash sensor wiring.
B169E-00›
DTC B169E-00 indicates the airbag electronic control unit (SRS ECU/ACU) detected a fault during its internal self-check. Specifically, this constitutes a hardware or logic fault in the ACU internal processor, memory (EEPROM/Flash), power management module, or internal communication bus, rather than a problem with external sensors, wiring harnesses, or crash detection circuits. This fault indicates the ACU cannot guarantee reliable execution of the airbag deployment logic during a collision, making it a safety-critical fault. In BYD Qin series vehicles, the ACU typically mounts in the center tunnel or beneath the dashboard and manages multiple deployment circuits, including the front airbags, side curtain airbags, and seat belt pretensioners.
B169E›
B169E (SRS_ECU Fault) indicates the Airbag Control Unit (ACU) detected an internal circuit abnormality, a power supply/ground fault, or a critical communication bus interruption. This fault code signifies the SRS ECU cannot execute the self-test procedure, or it detected a functional failure in the internal processor, memory, or ignition loop monitoring circuit. This is a Hard Fault, meaning the airbag system may be in a complete failure or degraded mode. In a collision, the airbags or pretensioners may fail to deploy, posing a severe safety hazard.
B16FB11›
DTC B16FB11 indicates abnormal continuity between the Supplemental Restraint System (SRS) crash sensor (or pressure sensor) signal circuit (the third wire, typically the SIG signal wire) and body ground. In the BYD SRS circuit architecture, the front crash sensor typically uses a three-wire system: power supply (+B), ground (GND), and signal (SIG). When the signal wire shorts to ground, the SRS ECU detects a continuous 0V (or near 0V) signal. This contradicts the pulse signal or specific voltage value present during normal operation, causing the ECU to determine a sensor circuit fault. This fault forces the airbag system into fail-safe mode and continuously illuminates the airbag warning lamp. In a collision, the airbags may fail to deploy or deploy unintentionally, posing a severe safety hazard.
B169F-00›
DTC B169F-00 indicates the Airbag Control Unit (SRS ECU) detected a severe internal self-check fault, preventing normal system operation. As the core of the passive safety system, the SRS ECU monitors subsystems in real time, including crash acceleration sensors, side pressure sensors, and seat occupancy detection. Upon detecting a collision, the ECU triggers the airbags, seat belt pretensioners, and high-voltage interlock cut-off. This fault indicates a hardware-level error in the internal ECU processor, memory unit, power management module, or communication interface, or a communication interruption or error between the ECU and the vehicle network (CAN/LIN). When this fault triggers, the SRS system enters fail-safe mode and the airbag warning lamp illuminates continuously. All airbags and pretensioners disarm and may fail to deploy during an actual collision. Additionally, the vehicle high-voltage system may fail to execute the collision power cut-off, creating a severe safety hazard.
B169F›
In BYD new energy vehicles, DTC B169F indicates an ESP (Electronic Stability Program) control unit communication fault, not an SRS airbag fault (early documentation may contain classification errors). This fault code indicates the powertrain CAN or chassis CAN bus fails to receive a valid data frame from the ESP control module (integrated into the vehicle stability system, typically located on the left side of the engine compartment or inside the left front wheel arch), or the received signal fails verification. This disables the Electronic Stability Program, traction control, anti-lock braking system (ABS), and advanced driver assistance functions relying on ESP signals (such as adaptive cruise control and lane keeping). Root causes include a physical-layer CAN bus communication interruption, abnormal terminating resistance, a control unit power supply/ground fault, or a software version mismatch.
B169F00›
DTC B169F00 indicates the Airbag Control Unit (SRS ECU) detected a severe fault during its internal self-test. As the core controller of the passive safety system, the SRS ECU integrates lateral/longitudinal acceleration sensors, the crash algorithm processor, and the ignition drive circuit. This DTC triggers when the ECU internal processor, memory (EEPROM/Flash), power monitoring module, or internal communication bus experiences an irreversible hardware or software anomaly. Upon detecting this fault, the ECU enters a degraded mode and may disable the ignition output for the airbags and seat belt pretensioners, resulting in partial or complete loss of crash protection functions. This safety-critical fault requires immediate action.
B16A0-00›
DTC B16A0-00 indicates the airbag control unit (SRS ECU/ACM) detected a severe fault during its internal self-test. This indicates a hardware-level anomaly in the ECU internal processor, memory, power regulation circuit, or safety monitoring circuit, rather than an external sensor or actuator fault. The SRS ECU integrates crash discrimination algorithms, firing decision logic, and fault diagnostic functions. This safety-critical fault means the ECU cannot guarantee reliable airbag and pretensioner deployment during a collision. The root cause may be internal EEPROM data corruption, CPU calculation errors, abnormal internal voltage monitoring, or watchdog circuit triggering. This fault typically requires ECU assembly replacement rather than repair.
B16A0›
DTC B16A0 indicates a fault in the passenger-side Occupant Classification System (OCS) rather than a purely SRS_ECU hardware fault. The system uses a pressure sensor matrix integrated into the front passenger seat cushion and the OCS control module to monitor front passenger seat occupancy and weight category (adult/child/empty) in real time, and sends commands to the SRS_ECU to suppress or allow airbag deployment. The OCS sets DTC B16A0 when it detects an open circuit, short circuit, abnormal signal, or loss of calibration data in the sensor circuit. This fault prevents the SRS_ECU from accurately determining the front passenger status, posing the following risks: 1) Unnecessary airbag deployment when the front passenger seat is empty, increasing repair costs; 2) Airbag suppression during a collision due to incorrectly identifying the passenger as a child, resulting in inadequate occupant protection; 3) Abnormal seat belt pretensioner operating logic. The system uses a 5V reference voltage circuit and is extremely sensitive to changes in circuit resistance and connector contact resistance.
B16A1›
DTC B16A1 indicates the airbag control unit (SRS ECU) detects an internal fault or abnormal communication with connected left-side safety system components. Specific causes include an SRS ECU internal processor error, memory fault, software anomaly, or a communication interruption with the left side impact sensor (left B-pillar), left seat belt pretensioner, or left seat occupancy detection sensor. This critical airbag system fault indicates the ECU may fail to receive left-side impact signals or execute airbag deployment commands. Consequently, the left side airbag, side curtain airbag, or seat belt pretensioner may fail to deploy during a side impact. This severely degrades vehicle passive safety protection and requires immediate repair.
B16A1-00›
DTC B16A1-00 indicates the Airbag Control Unit (ACU) detected a communication anomaly or internal circuit fault in the Left Side Impact Sensor. The SRS_ECU continuously monitors the supply voltage, signal circuit resistance, and LIN/CAN communication frame rate of each impact sensor. The ECU sets this DTC if it detects an open circuit, short to ground, or short to power in the left sensor wiring, or a sensor data validation error (e.g., capacitance drift, acceleration signal out of range) lasting over 200ms. Once set, the system enters a degraded mode. This mode may disable the left side airbag and curtain airbag deployment, or on certain models, restrict the entire airbag system, posing a severe safety hazard.
B16A100›
DTC B16A100 actually indicates an AVAS (Acoustic Vehicle Alerting System) fault, not an SRS airbag system fault. This DTC signifies the Pedestrian Warning Speaker has an open or short circuit, or the AVAS control module detects a speaker circuit fault. AVAS is a mandatory safety feature on new energy vehicles that simulates engine sound to warn pedestrians at low speeds (0-20 km/h). The system triggers this DTC when it detects abnormal speaker circuit resistance (normal range: 4-8 Ω), a wiring short to ground or open circuit, or an internal control module fault. This disables the low-speed warning sound and compromises safety compliance.
B16A2-00›
B16A2-00 indicates an internal fault or performance degradation in the airbag control unit (SRS ECU). This is not an external sensor or actuator issue, but an abnormality in the microprocessor, memory chip, power management module, or internal acceleration sensor on the ECU main board. This fault causes the airbag system to enter a degraded mode or fail completely. Front airbags, side airbags, and pretensioner seatbelts may fail to deploy normally during a collision. It may also trigger a high-voltage interlock cut-off, preventing the vehicle from powering up or causing a loss of high voltage while driving. This DTC is a Hard Fault. Simply disconnecting the power usually cannot clear it. Perform an in-depth diagnosis of the hardware or software status.
B16A2›
DTC B16A2 indicates the airbag control unit (SRS ECU) detects an internal fault or system-level communication error. As the core control module of the passive safety system, the SRS ECU monitors crash sensor signals, deploys airbags and seat belt pretensioners, and executes post-collision fuel cut-off protection. This DTC indicates an anomaly in the ECU internal processor, memory, or communication interface. It also triggers upon detecting a power/ground circuit fault, CAN bus communication interruption, or crash data lock (incorrectly reset after a collision). This fault may prevent the airbag system from deploying during an actual collision or cause related functions, such as seat belt pretensioners and seat occupancy detection, to fail. This severe fault compromises driving safety.
B16A3-00›
DTC B16A3-00 indicates an internal self-check failure or core function fault within the airbag control unit (SRS ECU). Specifically, this code indicates the ECU detects an internal processor fault, EEPROM memory error, abnormal internal power reference voltage, or SRS-CAN (Supplemental Restraint System CAN bus) communication interruption during the startup self-check or operation. In BYD Qin series models, the SRS ECU integrates crash criteria algorithms, high-voltage interlock cut-off control logic, and multi-sensor data fusion functions. This fault causes the airbag system to enter Fail-Safe mode, disabling the deployment of airbags, side curtain airbags, seat belt pretensioners, and the high-voltage system emergency cut-off function, while illuminating the instrument cluster SRS warning lamp. If a collision occurs, the occupant protection system will fail and the high-voltage battery may not disconnect automatically, creating an extremely high safety risk.
B16A3›
DTC B16A3 indicates an internal fault in the airbag electronic control unit (SRS ECU, also known as the ACU - Airbag Control Module). This fault points to an abnormality within the ECU processor, memory (EEPROM), power supply monitoring circuit, or safety sensor monitoring circuit, rather than an issue with external airbags, sensors, or wiring harnesses. The ECU internal self-diagnostic program triggers this DTC when it detects key circuit parameters exceeding thresholds (e.g., internal voltage reference deviation, memory checksum failure, or watchdog reset). This fault may prevent the airbag system from deploying normally during a collision or create a risk of unintended deployment. It constitutes a core fault in the passive safety system and requires immediate resolution.
B16A4-00›
DTC B16A4-00 indicates the airbag control unit (SRS ECU) detects an internal or systemic fault. As the core control module of the safety system, the SRS ECU monitors crash sensor status, controls the firing and deployment of airbags and seat belt pretensioners, and communicates with the vehicle CAN network. This fault indicates potential hardware damage, software malfunction, or power/communication interruption in the ECU’s internal microprocessor, memory, power regulation circuit, or communication interface. When this DTC triggers, the SRS system enters fail-safe mode. All airbags (driver, passenger, side, and curtain) and seat belt pretensioners may fail to deploy during a collision. The instrument cluster continuously illuminates the airbag warning light, severely compromising passive safety protection.
B16A4›
DTC B16A4 indicates the airbag control unit (SRS ECU) detected an internal system fault or critical support circuit abnormality. As the core of the passive safety system, the ECU processes real-time data from the front and rear crash sensors, side pressure sensors, and accelerometers. It determines airbag deployment, seat belt pretensioner activation, and high-voltage interlock disconnection. This DTC triggers when the ECU self-diagnostic detects an internal CPU processing error, an EEPROM memory checksum failure, a transient voltage drop at the power supply monitoring circuit, or a communication interruption between the master and slave safety chips. In this condition, the system enters fail-safe mode. This mode may disable all airbag deployment functions and fails to guarantee normal protection logic during a collision, creating a severe safety hazard.
B16A5›
DTC B16A5 indicates an internal self-diagnostic fault in the airbag control unit (SRS ECU). The SRS ECU is the core control module of the safety system, responsible for monitoring crash sensors and controlling airbag deployment, seat belt pretensioners, and seat occupancy detection. This fault code specifically points to a hardware-level abnormality in the ECU internal processor, memory (EEPROM/Flash), power supply monitoring circuit, or clock circuit, rather than an external wiring or sensor fault. This internal fault can force the airbag system into fail-safe mode, preventing normal airbag deployment during a collision or creating a risk of unintended deployment, making it a severe safety fault. Upon detecting the fault, the ECU illuminates the airbag fault warning light and may disable related functions such as the seat belt pretensioners and child monitoring system.
B16AE›
DTC B16AE indicates the Supplemental Restraint System (SRS) detects a squib encryption verification failure or abnormal encrypted communication in the ignition circuit. In BYD vehicles, the airbag ECU uses an encrypted communication mechanism (Ignition Encryption Protocol) with each airbag module and seat belt pretensioner to prevent accidental deployment or malicious interference. The SRS ECU stores this fault code when it cannot verify the squib identity encryption key, or when it detects ignition circuit resistance outside the standard range (typically 2.0-3.0Ω) accompanied by an abnormal encryption signal. This fault may prevent the corresponding airbag from deploying normally during a collision, or trigger the system to enter fail-safe mode (disabling some airbag functions).
B16A7-00›
The definition of DTC B16A7-00 varies across BYD vehicle platforms. In early models such as the Qin 100, Qin 80, and Qin EV450, this code indicates an internal fault in the SRS_ECU (airbag control unit). It signifies an abnormality in the main control chip, internal memory, or ignition circuit driver, preventing the airbag system from executing collision detection and airbag deployment logic. DM-i and e-Platform 3.0 models, such as the Qin PLUS, Song Pro, and Tang DM, often reuse this DTC as a hardware fault code for the seat occupancy recognition sensor (SBR) or the ultrasonic radar/blind spot monitoring radar. This indicates the ECU received an invalid or out-of-range sensor signal. Regardless of the definition, this fault causes the airbag system to enter degraded mode and illuminates the instrument cluster SRS warning lamp. It may also cause seat belt pretensioner failure, airbag suppression, or a risk of unintended deployment. Repair immediately.
B16A7›
DTC B16A7 indicates the airbag control unit (SRS ECU) internal self-check detected a systemic fault. This fault involves abnormalities in the SRS ECU internal microprocessor, memory (EEPROM/Flash), power management circuit, or watchdog circuit. Specific causes include an internal 5V/3.3V reference voltage regulator fault, an acceleration sensor (Satellite Sensor) communication timeout, an internal algorithm self-check failure, or a non-volatile memory data checksum error. Upon detecting this fault, the SRS ECU enters Fail-Safe Mode. This mode may disable some or all airbag deployment and seat belt pretensioner activation functions, and illuminate the instrument cluster airbag warning light. Because the airbag system is a critical passive safety system, this fault indicates the vehicle may fail to provide the designed occupant protection during a collision, creating a severe safety hazard.
B16AC-00›
DTC B16AC-00 indicates an internal hardware or software fault in the airbag control unit (SRS ECU), specifically a malfunction in the ECU internal processor, memory, power management circuit, or reference voltage circuit. This core control module fault may cause the airbags to fail to deploy during a collision or deploy unintentionally in non-collision situations, severely compromising occupant passive safety. Abnormal ECU internal voltage regulation circuits (5V reference voltage fluctuation), main control chip (e.g., NXP SPC5604) processor errors, crystal oscillator failure, internal memory data corruption, or lost configuration parameters typically cause this fault, rather than external sensor or wiring harness issues.
B16AC›
For BYD new energy models (Qin, Tang, Song, Yuan, and Han series), DTC B16AC indicates an air conditioning evaporator temperature sensor circuit fault (Evaporator Temperature Sensor Circuit Range/Performance), not the SRS_ECU fault stated in the original information. This NTC thermistor mounts on the air conditioning evaporator surface. It monitors the evaporator temperature in real time to prevent surface icing from blocking the air ducts. The controller sets this DTC and triggers the air conditioning system protection strategy (compressor shutdown or restricted cooling) upon detecting an out-of-range sensor signal voltage (close to 5V during an open circuit, close to 0V during a short circuit, or unresponsive to temperature changes), abnormal resistance, or an abnormal sampling frequency. This fault results in a lack of cooling, intermittent A/C operation, or evaporator icing.
B16AC00›
B16AC00 (Config_Error) indicates the internally stored configuration data in the airbag control unit (SRS ECU/ACU) does not match the actual vehicle hardware configuration, or the configuration data checksum failed. In BYD E2, E3, Qin EV, and similar models, this fault typically means the ACU coding data and vehicle configuration parameters (such as airbag quantity, seat belt pretensioner configuration, crash sensor type, and child seat recognition configuration) do not match the actual installed equipment, or data corruption occurred during writing or storage. This fault forces the SRS system into fail-safe mode, potentially disabling airbag deployment or causing complete system failure. This is a critical fault affecting passive safety.
B16AD-00›
DTC B16AD-00 indicates an internal fault or communication error in the Supplemental Restraint System Electronic Control Unit (SRS ECU). As the core module of the airbag system, this control unit monitors vehicle collision acceleration in real time, processes crash sensor signals, determines airbag deployment timing, and drives the ignition circuits. This fault may force the airbag system into Fail-Safe Mode, preventing the front dual airbags, side airbags, and curtain airbags from deploying during a collision. The condition may also cause seat belt pretensioner failure and disrupt the crash fuel cut-off function. The root cause typically involves an ECU internal microprocessor or memory failure, an abnormal 12V power supply (overvoltage/undervoltage), or an ECU malfunction resulting from a CAN network communication disruption, rather than a single sensor fault.
B16AD›
DTC B16AD indicates an internal fault or critical communication error in the airbag control unit (SRS ECU). This fault points to a hardware-level failure in the ECU internal microprocessor, non-volatile memory (EEPROM/Flash), power management module, or acceleration sensor interface circuit, rather than an external wiring issue. The ECU sets this code when its self-check detects a failed internal diagnostic test, a calibration data checksum error, a watchdog reset, or a critical circuit voltage deviating from threshold limits. This fault forces the SRS system into fail-safe mode: the system either completely disables the airbags (no deployment during a collision) or enters a degraded mode (only partial circuits operate), and illuminates the airbag warning lamp. Because this fault affects the passive safety system, the vehicle remains drivable but poses a severe safety risk.
B16AE00›
Internal fault in the SRS_ECU (airbag control unit) or systemic power supply/communication fault. This DTC indicates the airbag control module detects a functional fault in its processor, memory, power management circuit, or internal communication bus, preventing the system from guaranteeing accurate crash detection and reliable airbag deployment. Upon triggering, the SRS system enters fail-safe mode, disables all airbag and seat belt pretensioner functions, and continuously illuminates the instrument panel airbag warning light. The system may fail to provide occupant protection during a collision, and other safety systems may experience limited functionality.
B16B0›
DTC B16B0 indicates the Airbag Control Unit (SRS ECU) internal self-diagnosis detected a critical function abnormality. This ECU integrates the main control MCU, backup power supply, crash sensors (accelerometers), and ignition driver circuit. An "internal fault" specifically refers to compromised ECU core hardware or firmware integrity, including internal voltage regulator module failure (e.g., 5V/3.3V reference voltage deviation), EEPROM data checksum errors, interrupted communication between the main and backup CPUs, crash sensor signal processing circuit faults, or ignition loop driver chip damage. This fault forces the airbag system into fail-safe mode. During a collision, the system may fail to deploy airbags or activate seat belt pretensioners. It also carries a risk of unintended deployment, classifying it as a highest-level safety-related fault.
B16B000›
DTC B16B000 indicates the airbag electronic control unit (SRS ECU) detects an internal system fault or a deployment circuit abnormality. This fault may involve an internal ECU processor fault, a power/ground abnormality, a CAN communication fault, or, more commonly, the driver-side airbag deployment circuit resistance falling outside the calibrated range (normal 2.0-3.0 Ω). When the ECU detects high circuit resistance (>5 Ω), an open circuit, low circuit resistance (<1 Ω), or a short circuit, it sets this code and illuminates the instrument cluster airbag warning lamp. The system enters fail-safe mode, and the airbag may fail to deploy during a collision.
B16B9-00›
DTC B16B9-00 indicates an Airbag Control Unit (SRS ECU) internal self-test failure. Specific causes include a microprocessor logic error, internal memory (EEPROM/Flash) data checksum failure, power management module anomaly, or internal accelerometer signal processing circuit fault. This indicates an ECU hardware or low-level software fault, not a peripheral wiring or sensor issue. Upon entering fail-safe mode, the ECU disables all airbags, seat belt pretensioners, and collision unlock functions. The instrument cluster airbag warning light remains illuminated, and the occupant protection system may fail to operate during a collision.
B16B9›
DTC B16B9 indicates the airbag electronic control unit (SRS_ECU) detects an internal hardware fault or critical communication anomaly. This fault involves a self-test failure of the ECU internal processor, non-volatile memory (NVM), or power management module. It may also indicate a communication interruption or data checksum error between the ECU and the vehicle CAN network (powertrain CAN or body CAN). When this fault triggers, the SRS system typically enters fail-safe mode, disabling airbag and seat belt pretensioner deployment during a collision, and illuminates the instrument cluster airbag warning light. This safety-critical fault requires immediate repair to ensure correct occupant restraint system operation.
B16BA-00›
DTC B16BA-00 indicates the Airbag Control Unit (SRS ECU) detected an abnormality during its internal self-check or lost normal function. This fault indicates an SRS ECU hardware failure, software malfunction, power supply or communication interruption, or internal algorithm error, rather than an external sensor or actuator issue. The SRS ECU serves as the core of the safety system and monitors the crash sensors, seat belt pretensioners, airbag ignition circuits, and occupant classification system. This fault forces the entire airbag system into fail-safe mode; the system may fail to deploy the airbags and pretensioners during a collision. The instrument cluster airbag warning light (AIRBAG/SRS light) remains illuminated, and some models trigger a buzzer alarm. Due to the highly integrated SRS ECU in Qin series models (especially 2017-2018 models), related communication or internal fault codes in the B16B0-B16BF range may accompany this fault.
B16BB›
DTC B16BB indicates the Airbag Control Unit (SRS_ECU) detected a severe fault during its internal self-test. This typically points to a hardware-level fault in the ECU internal processor, memory, power regulation circuit, or ignition driver circuit. This means the SRS_ECU cannot execute the crash detection algorithm, cannot drive the airbag ignition circuits, or detected a program memory error during the cyclic redundancy check (CRC). This safety-critical fault forces the entire airbag system into fail-safe mode. During a collision, all airbags (front airbags, side curtain airbags, knee airbags) and seat belt pretensioners may fail to deploy. The fault may also affect the active head restraint and crash fuel cut-off functions.
B16BA›
DTC B16BA indicates an internal fault or system-level communication fault in the airbag control unit (SRS ECU). As the core controller of the passive safety system, the SRS ECU monitors crash sensor signals, evaluates crash severity, triggers airbag and seat belt pretensioner deployment, and continuously performs system self-diagnostics. This DTC typically indicates an internal ECU microprocessor fault, an EEPROM data checksum failure, a power supply monitoring circuit abnormality, or a CAN bus communication interruption. The ECU sets this DTC and enters degraded mode when it detects an internal circuit fault, a supply voltage outside the normal 9-16V range, or a loss of communication with the vehicle network exceeding the specified time (typically >500ms). In this state, the vehicle may completely lose crash protection functions (airbags will not deploy) or risk unintended deployment. This constitutes a high-risk safety fault.
B16BB-00›
DTC B16BB-00 indicates the Airbag Control Unit (SRS ECU) internal self-check detected a critical fault. This fault involves a hardware-level abnormality in the ECU internal processor, memory module, or power management unit, which may cause the airbag system to fail to deploy during a collision or deploy unintentionally in non-collision situations. This DTC indicates a permanent hardware fault that a simple code clear usually cannot resolve. Thoroughly inspect the ECU power supply stability, CAN communication integrity, and internal circuit board condition. In BYD Qin series vehicles, this ECU integrates crash decision algorithms and multi-point sensor data processing functions. The fault triggers the system to enter safety protection mode, disabling airbag deployment for safety.
B16BC-00›
DTC B16BC-00 indicates the airbag control unit (SRS ECU) internal self-check detected a severe fault, causing the system to enter fail-safe mode. This fault involves hardware failures or data checksum errors in core ECU components, including the main control processor (MCU), internal acceleration sensor (G-sensor), power management module, or memory (EEPROM/Flash). When this fault occurs, the SRS ECU may fail to accurately assess collision severity, preventing passive safety devices such as airbags and seat belt pretensioners from deploying correctly during a crash, or creating a risk of unintended deployment. The system illuminates the instrument cluster airbag warning light and disables the entire airbag system. The vehicle remains drivable but loses crash protection functions, constituting a severe fault that affects driving safety.
B16BC›
DTC B16BC indicates the airbag control unit (SRS ECU) detects an internal system fault or critical safety circuit abnormality. Specifically, this fault typically indicates an SRS ECU internal processor self-test failure, corrupted non-volatile memory (NVM) data, a power management module fault, or a communication interruption between the driver-side Occupant Classification System (OCS) and the ECU. BYD e-platform models integrate the SRS ECU near the body control module. The ECU monitors crash sensors, seat belt pretensioners, airbag ignition circuits, and seat occupancy status. This fault may prevent the airbag system from deploying correctly during a collision or trigger a warning without a collision. It constitutes a critical fault affecting passive safety.
B16BD-00›
DTC B16BD-00 indicates a LIN (Local Interconnect Network) bus communication fault between the Body Control Module (BCM) and the left front window motor. Some early documents label this code as SRS-related; however, it actually indicates a loss of communication or abnormal signal voltage at the left front window motor (LHD Driver Door Motor). The LIN bus uses a single-wire circuit (typically green/white) with a normal operating voltage of 9-11V. The BCM sets this DTC if it fails to receive a response signal from the motor within the specified time, or if it detects a bus open, short to ground, or short to power. This fault disables left front window operation and the anti-pinch function. The BCM may also enter protection mode and cut power to the motor.
B16BD›
SRS ECU (Airbag Electronic Control Unit) internal self-test fault or abnormal external communication/power supply. This DTC indicates the Airbag Control Unit (ACU) detected a functional fault in its processor, memory, power management circuit, or critical sensor interfaces during the self-test. This triggers the system to enter fail-safe mode (disabling all airbags, seat belt pretensioners, and the crash fuel cut-off function). Specific fault conditions include: 1) ECU internal hardware damage (e.g., BGA chip cold solder joints or aging electrolytic capacitors); 2) Abnormal impedance in the 12V power supply or ground circuit causing an ECU reset; 3) CAN network communication interruption (loss of synchronization with the vehicle control unit and instrument cluster); 4) Short or open circuit in the signal links of critical safety sensors (front impact sensor, side impact pressure sensor, seat occupancy sensor) exceeding the calibrated threshold. This fault may prevent airbag deployment during a collision or risk unintended static deployment. Immediately remove the vehicle from service and perform repairs.
B16BE-00›
DTC B16BE-00 indicates the airbag control unit (SRS ECU) detected a critical internal functional fault. This condition represents a functional failure in the ECU internal microprocessor, memory, power regulation circuit, or internal self-test logic, preventing the control unit from executing its safety monitoring algorithms. The ECU sets this DTC during the power-on self-test if it detects an internal data checksum failure, abnormal core circuit operation, or an internal communication bus fault. This fault forces the SRS system into fail-safe mode, potentially preventing the airbags and seat belt pretensioners from deploying correctly during a collision, or in extreme cases, creating a risk of unintended deployment. This is a critical fault affecting occupant passive safety.
B16BE›
DTC B16BE indicates an internal fault or functional failure of the airbag system electronic control unit (SRS ECU). The SRS ECU is the core module of the safety system. It monitors the crash acceleration sensors in real time, processes the crash algorithm, and controls the deployment strategy for the airbags and seat belt pretensioners. The ECU internal self-check routine detects this hardware abnormality, which may involve: a main processor (MCU) calculation error, a non-volatile memory (NVM) data integrity check failure, abnormal output from the internal power regulation circuit, a safety monitoring watchdog timeout, or a deployment circuit driver chip fault. The ECU immediately enters Fail-Safe mode, disconnects power to all airbag deployment circuits, and disables airbag deployment to prevent unintended triggering, resulting in a loss of occupant protection during a collision. This fault is a Hard Fault. Disconnecting power or clearing the code usually cannot resolve it. Perform a hardware-level repair or replace the unit.
B16BF-00›
B16BF-00 indicates the airbag control unit (SRS ECU) detected an internal fault or critical function failure. This DTC represents a core Safety System fault, indicating the SRS ECU cannot execute crash detection algorithms, airbag deployment logic, or communication with other safety modules (such as seat belt pretensioners, crash sensors, and the vehicle CAN network). Specific causes include an ECU internal processor or memory fault, a power management module anomaly, a damaged deployment circuit driver chip, a Safing Sensor self-test failure, or an EEPROM data checksum error. This fault forces the entire airbag system into fail-safe mode. During a collision, the system may fail to deploy the driver airbag, front passenger airbag, side airbags, and seat belt pretensioners, posing a severe safety hazard.
B16BF›
DTC B16BF indicates an internal fault in the airbag electronic control unit (SRS ECU) or a system-level functional failure. This fault involves an ECU internal processor self-check anomaly, memory checksum failure, power management module fault, or CAN communication interface fault. The SRS ECU continuously monitors the internal operating voltage (3.3V/5V regulated output), EEPROM data integrity, watchdog timer status, and communication quality with the vehicle CAN network. The system sets this DTC when the ECU detects an internal circuit fault, supply voltage outside the 9-16V range, excessive ground resistance (>1Ω), or CAN signal distortion. This safety-critical fault may cause complete airbag system failure (airbags fail to deploy during a collision), unintended deployment, or seat belt pretensioner failure.
B16C0-00›
DTC B16C0-00 indicates the Airbag Electronic Control Unit (SRS ECU) detected an abnormality during its internal self-check. This typically indicates a hardware fault in the ECU internal processor, memory, or power management module, or a communication failure between the ECU and the vehicle CAN network. This fault forces the airbag system into fail-safe mode. In a collision, the system may fail to deploy the airbags and seat belt pretensioners, or activate the high-voltage interlock cut-off function, posing a severe safety risk. This DTC is a hard fault and generally will not clear automatically. Perform a hardware-level repair or replace the ECU.
B16C0›
On BYD vehicles, DTC B16C0 indicates a front passenger Occupant Classification System (OCS) sensor fault, not an internal SRS ECU fault. The system detects seat load status using a capacitive or piezoresistive pressure-sensing membrane inside the front passenger seat cushion. It distinguishes between an adult, a child, or an unoccupied seat to control the front passenger airbag deployment strategy (deployment decision, timing, and force). When the SRS ECU detects an OCS sensor signal open circuit, short circuit, out-of-range value, or incomplete calibration, it sets this DTC and illuminates the airbag warning lamp. This fault creates an extreme safety risk: the system may incorrectly identify the seat as unoccupied and disable airbag deployment, or erroneously deploy the airbag when a child seat is installed. This safety hazard requires immediate repair.
B16C1-00›
DTC B16C1-00 indicates an internal fault or functional failure of the airbag system electronic control unit (SRS_ECU). This fault represents a core self-check abnormality of the airbag control module. It typically indicates a hardware-level fault in the ECU internal processor, memory, power management circuit, or safety monitoring circuit. This fault causes the airbag system to enter a degraded mode or complete failure state. During a collision, the system may fail to deploy the airbags, making this a critical fault affecting vehicle passive safety. Upon fault detection, the SRS system typically illuminates the instrument cluster airbag warning light (solid) and logs a non-clearable hard fault code. Some models may also trigger the seat belt pretensioner disable logic.
B16C1›
DTC B16C1 indicates the airbag control unit (SRS ECU) detected an internal system fault or an external power supply or communication abnormality. Specifically, this code points to a functional failure in the ECU power management module, internal memory (EEPROM/Flash) self-check, watchdog timer, or main processor. The SRS ECU triggers this fault code and illuminates the airbag warning lamp if it detects an operating voltage outside the 9-16V range, an internal data verification failure, or a loss of communication with the vehicle CAN network during the ignition cycle self-check. This fault forces the airbag system into a degraded mode. During a collision, the system may fail to deploy the airbags or actuate the seatbelt pretensioners, posing a severe safety hazard.
B16C2-00›
DTC B16C2-00 indicates the airbag control unit (SRS ECU) detected a critical fault during its internal self-check, forcing the system into fail-safe mode. This fault involves a hardware-level abnormality in the ECU internal microprocessor, non-volatile memory (NVM), power management module, or safety monitoring circuit. The ECU sets this code upon detecting an internal watchdog reset, checksum verification failure, integrated acceleration sensor (MEMS) signal processing circuit abnormality, or safety communication interruption between the main and secondary CPUs. In BYD Qin series vehicles, this fault prevents the entire airbag system (including driver/passenger front airbags, side airbags, curtain airbags, and seat belt pretensioners) from deploying. It may also interrupt communication with the powertrain CAN and body CAN, causing the instrument cluster to illuminate the airbag warning lamp continuously. Unlike sensor or ignition circuit faults, this DTC indicates a functional failure of the ECU itself. Inspect the ECU installation environment (the area beneath the center tunnel is susceptible to water ingress) and verify power supply stability.
B16C4-00›
B16C4-00 indicates the airbag control unit (SRS ECU) detects an internal fault or critical communication anomaly. This fault code indicates the ECU self-diagnostic detected an error in the processor, memory, power supply monitoring circuit, or internal safety logic, or the ECU lost communication with the crash sensors or airbag modules. Because the SRS ECU is the core of the passive safety system, this fault causes the airbag system to enter fail-safe mode. During a collision, the front, side curtain, or knee airbags may fail to deploy, and the seat belt pretensioners may also fail. When this fault triggers, the ECU typically cuts power to the airbag ignition circuits to prevent inadvertent deployment.
B16C2›
DTC B16C2 indicates an internal hardware or software self-test failure in the airbag control unit (SRS ECU). This fault signifies a functional failure in the ECU internal microprocessor, EEPROM memory, crash sensor interface circuit, or firing circuit driver. The ECU performs internal diagnostics at each power-up. If the ECU detects a CPU calculation error, memory checksum failure, internal communication bus fault, or firing circuit driver chip abnormality, it sets this DTC and enters fail-safe mode. The airbag system completely disables, and the airbags may fail to deploy during a collision. This condition also affects related systems such as the seat belt pretensioners and airbag warning lamp. This constitutes a hard fault and typically will not clear by simply disconnecting power. Replace the ECU or repair the internal hardware.
B16C3-00›
BYD strictly defines B16C3-00 as an open circuit or excessive resistance fault in the driver airbag (DAB) stage 1 ignition circuit. Although the original description states "SRS_ECU fault", it actually indicates a communication or circuit anomaly between the driver airbag module and the SRS control unit, rather than an ECU hardware failure. This fault indicates the airbag control module (ACM) detects the driver-side airbag ignition circuit resistance falls outside the normal range (standard value 2.0±0.1Ω). This typically presents as infinite resistance (open circuit) or greater than 5Ω (poor connection). When this fault activates, the airbag system enters fail-safe mode, the driver-side airbag will not deploy during a collision, and the instrument cluster SRS warning light remains illuminated.
B16C3›
DTC B16C3 indicates a functional fault in the airbag system electronic control unit (SRS_ECU). The SRS_ECU is the core controller of the safety system. It monitors crash sensor signals in real time, processes crash algorithms, controls the deployment timing of the airbags and seat belt pretensioners, and manages the communication network of the entire passive safety system. This DTC usually indicates an internal processor or memory fault in the ECU, or a loss of communication between the ECU and the vehicle CAN network. An intermittent open circuit in the ECU power supply or ground circuit can also trigger this fault. This fault causes the airbag system to enter fail-safe mode. The airbags may fail to deploy in a collision, creating a serious safety risk.
B16C4›
DTC B16C4 indicates an internal fault or severe communication failure in the airbag control unit (SRS ECU). This fault indicates a functional failure of the microprocessor, memory, or power management module within the SRS ECU, or a communication interruption between the ECU and the vehicle CAN network or sensor array. The SRS ECU serves as the core controller of the passive safety system. It receives crash sensor signals, determines collision severity, and triggers protective devices such as airbags and seat belt pretensioners. This critical fault compromises occupant safety by potentially preventing normal airbag deployment during a collision, or by creating a risk of false alarms and unintended deployment. When this fault occurs, the SRS system typically enters fail-safe mode, cuts off the airbag ignition circuit to prevent unintended deployment, and illuminates the instrument cluster airbag warning light.
B16C5›
DTC B16C5 indicates an internal fault or critical function failure in the airbag control unit (SRS ECU). The SRS ECU is the core controller of the safety system. It monitors vehicle collision acceleration, processes crash signals, and controls the ignition triggering of protective devices such as airbags and seat belt pretensioners. The following conditions trigger this DTC: ECU internal main control chip (MCU) self-test failure, abnormal internal acceleration sensor signal, ignition circuit driver fault, EEPROM read/write error, or persistent ECU power supply voltage or communication bus abnormalities. When this fault occurs, the SRS system may enter fail-safe mode, preventing normal airbag deployment during a collision or, in extreme cases, causing unintended deployment. This critical fault directly compromises occupant safety.
B16C6-00›
DTC B16C6-00 indicates the Airbag Control Unit (SRS ECU) detected an internal self-check fault or abnormal communication with the vehicle network. The SRS ECU is the core controller of the passive safety system, monitoring crash sensors, seat occupancy detection, seat belt pretensioners, and individual airbag modules. When this DTC triggers, the ECU may enter fail-safe mode, degrading or completely disabling the entire airbag system. As a result, the front dual airbags, side airbags, and pretensioning seat belts may fail to deploy during a collision. This is a hard fault and will not clear automatically after a vehicle restart. Troubleshooting requires professional diagnostic equipment.
B16C6›
DTC B16C6 (Left Front Seat Belt Pretensioner Deployment Control Circuit Low) indicates a low voltage or open circuit in the left front (driver side) seat belt pretensioner deployment control circuit. This SRS (Supplemental Restraint System) subsystem fault involves the pyrotechnic pretensioner inside the seat belt retractor and its control circuit. The airbag control unit (ACU) sets this DTC when it detects pretensioner circuit resistance outside the standard range (normally 2.0±0.1Ω), an open circuit, a short to ground, or abnormal voltage. This fault forces the airbag system into a degraded mode. During a collision, the left front seat belt pretensioner may fail to deploy and retract, severely compromising driver protection. The instrument panel SRS warning lamp remains illuminated to indicate system failure.
B16C7-00›
DTC B16C7-00 indicates an internal fault or communication error in the SR8 panoramic image control unit (360° surround-view system ECU). This ECU typically mounts on the right side of the trunk or inside the center console. It processes video signals from the front, rear, left, and right surround-view cameras to enable the bird’s-eye view, dynamic guide lines, dashcam, and reversing camera functions. This DTC triggers when the ECU self-check detects a processor fault, memory error, unstable power supply, or CAN network communication interruption, forcing the system into fail-safe mode. The multifunction display may go black, show a "Panoramic System Fault" warning, or display only a single camera view. Although this fault does not affect the powertrain or driving safety, the vehicle loses parking assistance functions, increasing the risk of a reversing collision. This fault frequently occurs in BYD Song series (Song Pro, Song MAX, Song PLUS) and early Qin EV models. Diagnostic tools often mislabel it as an "SRS_ECU fault"; it is actually an SR8 system fault.
B16C7›
DTC B16C7 indicates the airbag control unit (SRS ECU/ACU) detected an internal system fault. This typically points to an abnormality in the ECU internal microprocessor, non-volatile memory (NVM), power supply monitoring circuit, or safety relay drive circuit. As a hard or persistent fault, it can force the airbag system into fail-safe mode and disable airbag deployment. On BYD e-platform and DM models, a gateway communication interruption may accompany this fault, affecting the normal drive logic of the instrument cluster airbag warning lamp. This Safety Level 2 fault requires immediate repair.
B16C8-00›
DTC B16C8-00 indicates an internal fault or critical function failure in the airbag control unit (SRS ECU, BYD internal code SR8). As the core of the passive safety system, this ECU monitors front and side impact sensor signals, vehicle deceleration, and seat belt status in real time. Upon detecting a collision, it controls airbag ignition, seat belt pretensioner activation, and high-voltage system power-off protection. This DTC triggers when the ECU self-check detects an internal processor fault, memory checksum error, power supply monitoring abnormality, or safety monitoring circuit failure, forcing the entire airbag system into fail-safe mode. In this state, the airbag system will not deploy regardless of collision severity. The vehicle may also restrict high-voltage power-on or enter limp mode. This severe fault compromises driving safety.
B16C8›
DTC B16C8 indicates a functional fault or internal self-check abnormality in the airbag control unit (SRS ECU). As the core control module of the passive safety system, this ECU integrates longitudinal/lateral acceleration sensors, safety sensors, and a microprocessor. It monitors real-time vehicle collision status, calculates collision severity, and controls the ignition and deployment timing of protective devices such as airbags, seat belt pretensioners, and knee airbags. The following conditions trigger this DTC: internal ECU processor faults (such as a damaged Freescale/NXP main control chip), EEPROM data checksum failures, power management circuit abnormalities, internal safety monitoring circuit protection events, or communication interruptions between the ECU and the vehicle CAN network. When this fault occurs, the SRS system enters fail-safe mode and the airbag warning lamp illuminates continuously. In extreme cases, the airbags may fail to deploy during a collision or deploy unintentionally while driving due to false detection, posing a severe safety hazard.
B16DF-00›
This fault code indicates the SRS (airbag) control unit detects a communication interruption or no connection with the Left Rear Impact Sensor. This sensor typically mounts in the vehicle’s left rear side panel, C-pillar, or rear door area to monitor side-impact acceleration signals. The SRS ECU triggers this fault if it fails to receive valid data from the sensor within a predetermined time, or if it detects circuit resistance outside the normal range (open or short circuit). This fault disables the vehicle’s side-impact detection function. The system may fail to accurately determine collision severity, suppressing normal deployment of the left rear side airbag/side curtain airbag. In some cases, this creates a risk of unintended airbag deployment in fail-safe mode.
B16DF›
DTC B16DF indicates the SRS (Supplemental Restraint System) ECU detects a communication interruption or physical disconnection of the Left Rear Impact Sensor. This sensor typically mounts in the vehicle's left rear quarter panel, C-pillar, or rear longitudinal beam area to monitor collision acceleration from the left rear. The ECU sets this fault code if it fails to receive a valid signal (including the sensor ID code, acceleration data, or heartbeat signal) within the preset monitoring period, or if it detects circuit resistance outside the normal range (typically greater than 10 kΩ or less than 1 Ω). This fault disables the left rear collision detection function. During a side impact or rear-end collision, the SRS ECU may fail to accurately assess collision severity, compromising the deployment strategy of the side airbags, curtain airbags, or seat belt pretensioners and posing a severe safety risk.
B16DF00›
This DTC indicates an interrupted communication link between the airbag control unit (SRS ECU) and the left rear crash sensor. The left rear crash sensor typically utilizes a MEMS capacitive accelerometer and mounts on the left rear side panel (C-pillar area) to monitor left rear collision acceleration. During the ECU initialization self-check or a drive cycle, if the ECU fails to detect the sensor bias voltage (normally a 2.5V reference voltage at a 2-3kΩ equivalent resistance), detects infinite circuit resistance, or reads a continuous high or low signal line voltage exceeding the threshold, it registers a 'not connected' state. This fault may prevent the left rear side airbag and curtain airbag from deploying correctly during a collision. The ECU simultaneously illuminates the airbag warning lamp and enters fail-safe mode (some models disable the entire side airbag circuit).
B16E0-00›
DTC B16E0-00 indicates a short to ground in the Left Rear Impact Sensor signal circuit within the Supplemental Restraint System (SRS). This sensor typically mounts in the left rear quarter panel or C-pillar area to monitor collision acceleration at the left rear of the vehicle. A short to ground indicates abnormal continuity (resistance below the normal range) between the sensor power wire, signal wire, or shield and the vehicle body metal frame. This causes the SRS control module to receive a continuous low-level signal. This fault forces the SRS into fail-safe mode and may cause the following: 1) The left rear side airbag/curtain airbag fails to deploy during an actual collision. 2) The system misinterprets the fault as a collision and inadvertently deploys the airbag. 3) Entire SRS functionality restricts, severely compromising passive safety performance.
B16E0›
DTC B16E0 indicates a short to ground in the Left Rear Impact Sensor signal circuit within the airbag system (SRS). This sensor typically mounts in the left rear C-pillar, the left side of the rear bumper, or the inside of the left rear fender to monitor left rear collision acceleration. A "short to ground" means the insulation resistance between the sensor signal line and body ground (GND) falls below the standard value (typically <1Ω). This causes the SRS control unit (ACU) to detect a continuous low-voltage signal (approaching 0V), preventing it from acquiring normal acceleration change signals. This fault forces the SRS into fail-safe mode, disabling the deployment function of the left rear side airbags (side curtain or rear seat airbags). In extreme cases, this condition causes unintended airbag deployment or failure to deploy during a collision, posing a severe safety hazard.
B16E011›
This DTC indicates an abnormally low-resistance connection (short circuit) between the signal circuit of the left rear side impact sensor (SIS) in the Supplemental Restraint System (SRS) and the vehicle body ground (GND). Under normal operating conditions, the impact sensor sends a specific voltage signal (typically a PWM or resistor divider signal) to the SRS control unit (ACU) to indicate its status. When a short to ground occurs, the ACU detects the circuit voltage remaining at or near 0V and a resistance well below the standard range (typically <1Ω), identifying a short-to-ground fault. This fault causes the SRS to enter fail-safe mode. The system illuminates the airbag fault warning lamp and disables the left rear side airbag and curtain airbag deployment functions to prevent accidental deployment caused by the short circuit. In a severe side-impact collision, the affected airbags may fail to deploy normally, posing a major safety hazard.
B16E100›
B16E100 is a BYD SRS (Supplemental Restraint System) proprietary fault code indicating an internal circuit fault or abnormal communication signal in the Left Rear Impact Sensor. This sensor typically mounts in the left rear C-pillar, D-pillar, or inside the rear bumper. It operates as a piezoelectric or MEMS accelerometer and communicates with the Airbag Control Unit (ACU) via the LIN bus or a hardwired connection. During this fault, the ACU cannot accurately receive the left rear impact acceleration signal. This failure may prevent the side curtain airbag and left rear seat belt pretensioner from deploying during a collision. In extreme cases, the abnormal signal risks unintended airbag deployment. The following conditions typically trigger this fault code: abnormal sensor supply voltage (below 9V or above 16V), LIN bus communication timeout (no valid data for over 500ms), or internal sensor self-check failure (accelerometer drift or EEPROM checksum error).
B16E200›
DTC B16E200 indicates the SRS (Supplemental Restraint System) control module detects a configuration data mismatch for the Left Rear Impact Sensor. Specifically, the sensor calibration parameters, hardware serial number, or installation position coding stored in the control module do not match the physical characteristics of the connected Left Rear Impact Sensor. This is a software/configuration fault, not a hardware open or short circuit. This fault causes the SRS to enter a degraded mode. The left rear impact detection function may fail or operate with abnormal trigger thresholds, affecting the deployment logic of the side curtain airbags and seat belt pretensioners. However, it typically does not disable the entire airbag system.
B16E300›
DTC B16E300 indicates a current monitoring anomaly or communication error in the Electronic Parking Brake (EPB) left rear wheel actuator (motor). The EPB control module sets this fault when it detects the left rear parking motor operating current exceeds the calibrated threshold (normal range approximately 8-15 A) or fails to establish valid communication with the left rear motor. Possible causes include an internal motor short or open circuit, mechanical binding, poor wiring connections, or a control module fault. When this fault triggers, the system enters a safety protection mode. This mode may prevent the electronic parking brake from releasing or applying, disable the Auto Hold function, and illuminate an instrument cluster warning. Extreme cases immobilize the vehicle or create a rollaway risk.
B16E7-00›
DTC B16E7-00 indicates the airbag system (SRS) detected a communication interruption or abnormal signal between the Middle Rear Impact Sensor and the SRS control module. This sensor typically mounts on a structural member in the middle rear of the vehicle (such as the lower C-pillar or rear panel crossmember) and monitors collision acceleration in the middle rear area. The SRS module sets this DTC if it fails to receive a valid signal from the sensor within the specified time, or if it detects an open or short circuit in the wiring. This fault may prevent the side curtain airbags, rear side airbags, or seat belt pretensioners from deploying correctly during a middle rear collision. This severely compromises passive safety protection and continuously illuminates the instrument panel airbag warning light.
B16E7›
DTC B16E7 indicates the airbag control unit (SRS ECU) cannot establish normal communication with the Middle Rear Impact Sensor. This sensor typically mounts in the vehicle's central rear area (such as the rear panel, rear floor, or near the C-pillar) and monitors rear collision acceleration. When the ECU detects an open sensor circuit, an internal sensor fault, or a communication interruption, it stores this fault code and illuminates the airbag warning light. Consequently, during a rear-end collision, the airbag system may fail to correctly determine collision severity and deploy the rear airbags or seat belt pretensioners in time, severely compromising passive safety functions.
B16E700›
DTC B16E700 indicates the airbag system (SRS) detects a communication interruption or physical disconnection of the Middle Rear Impact Sensor. This sensor, typically located on the inner rear bumper reinforcement or lower C-pillar, monitors rear-end collision acceleration. A "not connected" status means the SRS control unit receives no valid signal from the sensor, typically indicating an open circuit or high-resistance condition. The system determines the sensor circuit is open, the connector is detached, or the sensor has internal damage. This fault causes the SRS to lose accurate rear-end collision monitoring capabilities. It may force the airbag control unit into a degraded protection mode, disable specific airbag functions, or illuminate the airbag warning lamp continuously, severely compromising passive safety system reliability.
B16E8-00›
This DTC indicates a short to ground in the signal circuit of the Supplemental Restraint System (SRS) Middle Rear Impact Sensor. The sensor mounts in the center of the rear bumper or rear longitudinal rail area. Electrically, the insulation resistance between the sensor signal wire (typically a LIN communication or analog signal line) and body ground drops below the threshold (generally <1Ω). This causes the SRS control unit (ACU) to continuously receive an abnormally low voltage signal. This fault forces the SRS into fail-safe mode. As a result, the system may fail to accurately detect rear impact acceleration, preventing the airbags, curtain airbags, or seat belt pretensioners from deploying in time during a rear-end collision. Furthermore, the ACU may interpret the condition as a wiring fault and completely disable the rear impact monitoring function, illuminate the instrument panel SRS warning lamp, and downgrade the vehicle's passive safety system. BYD Qin series models typically use a dual-axis accelerometer design for this sensor. The ACU continuously registers a short to ground as 'abnormal circuit current' or 'signal voltage below lower limit'.
B16F0-00›
B16F0-00 indicates a short to body ground in the Supplemental Restraint System (SRS) Right Rear Impact Sensor signal circuit. This sensor typically mounts in the C-pillar or right rear quarter panel area to monitor collision acceleration at the right rear of the vehicle. The SRS ECU logs this fault code when it detects abnormal voltage to ground on the sensor signal wire (continuous low level or excessively low impedance). This fault prevents the SRS ECU from accurately receiving the right rear impact signal. It may cause the airbag system to fail to deploy correctly during a side or rear impact, or to deploy inadvertently under normal conditions. Consequently, the system enters fail-safe mode, illuminates the airbag warning light, and may disable certain airbag functions.
B16E8›
DTC B16E8 indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance path (short to ground) between the Center Rear Impact Sensor (typically installed on the rear panel or C-pillar area) signal circuit and body ground. This sensor uses a piezoelectric or capacitive accelerometer. During normal operation, it outputs a 0.5-4.5V analog voltage signal to the SRS control unit to reflect collision acceleration. A short to ground causes the control unit to continuously receive a voltage signal near 0V, triggering the following: 1) The system determines the sensor has failed, enters fail-safe mode, and disables the associated airbags (including side curtain airbags and rear collision protection functions); 2) During an actual rear collision, the system cannot accurately identify collision severity, causing delayed or no airbag deployment; 3) If the short-circuit resistance is unstable, it triggers an intermittent fault, causing the SRS warning lamp to illuminate erratically. This is a hard fault. Upon detection, the control unit stores the DTC and illuminates the instrument cluster airbag warning lamp.
B16EF-00›
DTC B16EF-00 indicates the SRS (Supplemental Restraint System) detects an open circuit or high resistance condition (typically exceeding 10kΩ) in the Right Rear Impact Sensor or Driver Seat Belt Pretensioner circuit. The system triggers this Hard DTC when it detects interrupted communication between the component and the airbag ECU, or abnormal resistance in the ignition circuit. In BYD Qin series models, this code typically indicates a LIN bus communication failure or hard-wired connection fault at the side impact acceleration sensor located in the right rear C-pillar or B-pillar. In Song Pro, Tang DM, Han EV, and other models, this code designates an open circuit in the driver-side seat belt pretensioner ignition circuit. Upon triggering, the SRS ECU illuminates the airbag warning light, disables the corresponding airbag deployment and pretensioner functions, and enters fail-safe mode. In extreme cases, this failure may result in a loss of occupant protection during a side impact.
B16EF›
DTC B16EF indicates the SRS (Supplemental Restraint System) control module detects a communication interruption or missing physical connection with the Right Rear Impact Sensor. This sensor typically mounts in the right C-pillar, rear door frame, or inside the right rear quarter panel to monitor collision acceleration changes on the right rear side of the vehicle. During a side-rear collision, the sensor transmits the acceleration signal to the SRS module to determine whether to deploy the right curtain and side airbags. A "not connected" fault means the SRS module cannot detect the sensor during initialization or periodic communication checks. Causes include an open circuit, disconnected connector, internal sensor open circuit, or abnormal module power supply. This fault disables the right rear collision protection function. As a safety-critical fault, it requires immediate repair.
B16EF00›
DTC B16EF00 indicates the airbag control unit (SRS ECU) detected a communication interruption or open circuit in the Right Rear Impact Sensor. This sensor, typically installed inside the right rear door, C-pillar, or inner rear fender, monitors collision acceleration in the vehicle's right rear area. The ECU determines a "not connected" state if it fails to receive a valid sensor signal (voltage signal or LIN bus data frame) within the specified period (typically 500ms), or if it detects circuit resistance outside the threshold (typically >10kΩ or <1Ω, depending on specific circuit design). This safety-related fault can prevent the side airbag and side curtain airbag from deploying during a right rear collision. The vehicle remains drivable, but the airbag system enters a degraded mode.
B16F0›
This DTC indicates an abnormally low-resistance connection between the Supplemental Restraint System (SRS) Right Rear Impact Sensor signal circuit and body ground. In the BYD SRS architecture, impact sensors utilize a dual-axis accelerometer design, transmitting a 0-5V analog voltage signal to the Airbag Control Unit (ACU) via hardwire. A short to ground continuously pulls the signal line voltage down to <0.5V (normal static voltage is approximately 2.5V). The ACU sampling circuit detects this abnormal voltage level and triggers the DTC. This fault forces the SRS into fail-safe mode, disabling the right rear side airbag and curtain airbag deployment while illuminating the airbag warning lamp. Because the short circuit can occur anywhere in the wiring harness, excessive short-circuit current (>2A) risks burning out the internal ACU drive circuit. This single-point failure directly compromises the vehicle's side-rear collision detection capability and, in extreme cases, prevents airbag deployment during a collision.
B16F100›
DTC B16F100 indicates an internal electrical fault or signal plausibility error in the right (passenger side) Side Impact Sensor (SIS). This sensor typically mounts inside the right B-pillar trim panel or right front door cavity. It monitors the acceleration change rate (Delta-V) during a side impact and transmits an analog voltage signal (normal range 0.4-4.6V) to the SRS airbag control unit via the LIN bus or a hardwired connection. Fault trigger conditions include internal accelerometer self-test failure, signal voltage continuously outside thresholds (too high/too low), sensor ID verification failure, or communication loss with the SRS module. This fault prevents the right side airbags and side curtain airbags from deploying correctly during a side impact, or forces the airbag system into a degraded protection mode (retaining only the driver's front airbag function). This is a safety-critical fault requiring immediate repair.
B16F200›
DTC B16F200 indicates the airbag control unit (SRS ECU) detects abnormal configuration parameters for the right rear side impact sensor (C-pillar/rear quarter panel). This is a configuration fault, not a hardware failure. The sensor ID, installation position parameters, sensitivity calibration data, or hardware identification code stored in the SRS ECU do not match the installed physical sensor. While the sensor still communicates, the ECU cannot correctly interpret its crash signal threshold, potentially causing unintended deployment or failure of the side airbags or curtain airbags. Common triggers include: failing to perform online configuration after replacing the sensor during collision repair, using non-OEM parts causing a hardware ID mismatch, losing configuration data after an SRS software update, or interrupting the programming process resulting in incomplete configuration.
B16F300›
DTC B16F300 indicates an abnormal communication link between the airbag control unit (SRS ECU) and the Rear Right Impact Sensor. This sensor typically uses a LIN bus or a dedicated digital communication protocol to exchange data with the SRS ECU to monitor collision acceleration on the rear right side of the vehicle. The ECU sets this communication fault when it fails to receive a valid data frame from the sensor within the specified time or receives data with a checksum error. This fault causes the SRS system to enter a degraded mode and disables the rear right collision detection function. In extreme cases, it may affect the correct deployment timing of the side airbags/side curtain airbags. This is a safety-related fault.
B16F511›
DTC B16F511 indicates an abnormally low-resistance connection between the first signal line (low-side reference line/signal return) of an SRS crash sensor (typically a front or side crash sensor) and body ground. This short to ground causes the SRS control unit (ACU) to detect an abnormal voltage near 0V, preventing it from correctly receiving the sensor acceleration signal. The system enters fail-safe mode and disables the corresponding airbag deployment function. In extreme cases, misinterpreting the crash signal may trigger unintended airbag deployment. This critical circuit fault in the active safety system directly affects the normal protective function of the occupant restraint system.
B16F612›
DTC B16F612 indicates a short to vehicle battery positive (B+, usually 12V) in the first signal circuit of an airbag system (SRS) sensor. On the BYD Qin PRO, this typically points to the first signal circuit (pressure sensor signal wire or communication wire) of the front passenger Occupant Classification System (OCS) sensor. During normal operation, this circuit voltage varies between 0-5V. A short to power pulls the voltage to 12V, preventing the SRS control unit (ACU) from correctly identifying the seat occupancy status. This fault triggers the safety system protection mechanism, which may disable the passenger-side airbag or seat belt pretensioner, or illuminate the airbag warning lamp continuously. This creates a risk of the airbag failing to deploy during a collision or deploying unintentionally.
B16F700›
For BYD Qin PRO (2018–2019) models, DTC B16F700 indicates a "Sensor line 1 configuration error" in the SRS (Supplemental Restraint System/airbag system). "Line 1" typically refers to the main power wire, signal wire, or CAN communication line of a crash sensor (e.g., front or side impact sensor). This fault indicates the ACU (Airbag Control Unit) detects the sensor circuit's electrical configuration does not match the calibration parameters. Possible causes include incorrect pin assignments, incorrect wiring harness connection order, or incorrect coding and matching after sensor replacement. This safety-critical fault disables the related airbag circuit, preventing deployment during a collision.
B16F811›
DTC B16F811 indicates an unintended electrical connection (short circuit) between body ground and the second circuit of a Supplemental Restraint System (SRS) sensor, typically the low-side drive line or signal return line. In BYD’s SRS architecture, this usually indicates a wiring fault in the seat belt pretensioner igniter, side impact sensor, or seat occupancy recognition sensor. The SRS control unit detects an abnormally low circuit resistance (approaching 0Ω) and triggers the safety protection mechanism. This disables airbag and pretensioner deployment to prevent injury from accidental activation. This constitutes a hard fault, indicating a very high probability of physical wiring damage or an internal component short circuit.
B16F912›
This is an SRS (Supplemental Restraint System / airbag system) DTC. It indicates a short to the vehicle power supply (12V/B+) in a safety-related sensor circuit—typically the second signal/communication line of the seat occupancy sensor, seat belt pretensioner sensor, or side impact sensor. In the BYD DTC structure, "B16F9" designates the second-row Occupant Classification System (OCS) or the seat belt anchorage sensor, and the "12" suffix indicates a short to power. This fault causes the Airbag Control Unit (ACU) to detect an abnormally high signal voltage. The ACU then triggers the safety protection mechanism and places the affected airbag circuit into fail-safe mode. In extreme cases, this prevents correct airbag deployment during a collision or generates false warnings. Consequently, the system illuminates the airbag warning lamp and prevents vehicle operation.
B16FC12›
DTC B16FC12 indicates the third wire of an SRS sensor (typically the signal or 5V reference wire) shorts to positive (B+ or 12V/5V supply). In the BYD Qin PRO SRS architecture, crash sensors, seat occupancy sensors, and side airbag sensors typically use a three-wire design (power, ground, signal). The "third wire" transmits the sensor status signal to the Airbag Control Unit (ACU) or receives the reference voltage. When this circuit shorts to power, the ACU detects an abnormally high voltage (near battery voltage or above 5V) and determines the sensor signal is unreliable. The ACU immediately illuminates the airbag warning light and sets the airbag system to fail-safe mode (deployment disabled). This prevents unintended deployment or failure to deploy during a collision. This fault compromises a core active safety function and requires immediate repair.
B16FD00›
DTC B16FD00 indicates the SRS (airbag system) control module detects a mismatch between the electrical characteristics of a sensor's third wire (typically the sensor identification/configuration wire) and the preset ECU configuration. In BYD Qin PRO models, this usually involves the ID recognition wire for the seat occupancy sensor (SBR) or seat belt pretensioner sensor. The third wire transmits the sensor part number, installation position, or calibration parameters to the SRS ECU, typically via a specific resistance value or voltage range. The ECU logs a configuration error when it detects an open circuit, short circuit, or resistance/voltage outside the calibrated range on this wire. Causes include installing non-genuine parts, misaligned pins, or resistance drift from wiring harness aging. Unlike standard short or open circuits, this fault indicates a hardware identity recognition failure. It can force the SRS into a degraded mode, affecting normal airbag deployment logic.
B16FE11›
DTC B16FE11 indicates a short to ground in the fourth circuit of the airbag system (SRS) crash sensor. In the BYD SRS architecture, the "fourth circuit" typically refers to the signal return or diagnostic feedback circuit of the right rear side crash sensor (located in the right C-pillar/rear bumper area). This circuit abnormally connects to body ground (GND), causing the SRS control unit to detect an abnormal sensor signal voltage (continuous low level) and fail to receive the crash acceleration signal correctly. This fault triggers the SRS degraded mode, potentially causing complete airbag system failure (non-deployment) or a risk of unintended deployment. This constitutes a safety-critical fault. In this DTC, "B" represents the body system, "16F" identifies the SRS subsystem, and "E11" specifically indicates a short to ground in the right rear sensor circuit.
B16FF12›
DTC B16FF12 indicates a short to the vehicle 12V power supply on the fourth circuit (typically the signal or CAN communication line) of an SRS (airbag system) crash sensor (such as the front crash sensor, side crash sensor, or seat occupancy sensor). In the BYD Qin PRO 4-wire sensor architecture, the fourth wire typically transmits sensor signals or diagnostic communications. When this circuit shorts to power, the SRS control unit (ACM) detects an abnormal voltage (continuous high level) and fails to receive the sensor acceleration signal correctly. This triggers the safety protection mechanism, forces the airbag system into fail-safe mode (system disabled), and illuminates the instrument cluster airbag warning lamp. This fault may prevent proper airbag deployment during a collision, posing a severe safety hazard.
B170000›
DTC B170000 indicates a configuration error on circuit 4 (typically the configuration identification line, backup signal line, or sensor type identification line) of the Supplemental Restraint System (SRS) crash or acceleration sensor. The SRS control unit detects that the connected sensor hardware model, wiring harness pin assignment, or internal coding data does not match the preset system configuration. Circuit 4 typically handles sensor identification, redundant signal transmission, or address coding. Incorrect circuit connections, incorrect sensor models (e.g., installing a left-side sensor on the right side or using a sensor from an incompatible model year), or incorrect control module software calibration trigger this fault. This prevents the SRS from accurately determining the crash sensor status, potentially causing the airbags to fail to deploy during a collision or to deploy unintentionally. This is a safety-critical fault.
B1704-00›
DTC B1704-00 indicates the SRS (Supplemental Restraint System) ECU detects an open circuit fault in the left curtain shield airbag ignition circuit. The SRS ECU continuously monitors the airbag inflator circuit resistance via an internal diagnostic circuit. When the resistance value exceeds the normal threshold (typically >10Ω or approaching infinity), the ECU registers a 'disconnected' state. This fault prevents the left curtain airbag from deploying during a side impact, depriving the occupant's head of lateral impact protection and posing a severe safety hazard. Interrupted electrical connections, damaged wiring harnesses, or a failed inflator within the airbag module can cause this fault.
B1704›
DTC B1704 indicates the Supplemental Restraint System (SRS) detects a communication circuit abnormality between the left curtain airbag (CAB) and the Airbag Control Unit (ACU). Specifically, the ACU detects the left curtain airbag squib circuit resistance falls outside the standard range (normally 2-3Ω), indicating an open circuit, short circuit, or poor connection. As a safety-critical fault, this condition prevents the left curtain airbag from deploying during a side impact, severely compromising occupant head protection. Potential causes include wiring issues, poor connector contact, or an internal squib failure within the curtain airbag assembly.
B17041B›
DTC B17041B indicates the SRS (Supplemental Restraint System) ECU detected an open circuit or abnormal resistance in the left curtain shield airbag circuit (typically >4.8Ω or <1.0Ω). This fault indicates an interrupted electrical connection between the left curtain airbag inflator and the SRS control unit. Causes include a disconnected connector, a wiring harness open circuit, or an internal open circuit within the curtain airbag assembly. This condition prevents the left curtain airbag from deploying during a side impact or rollover event, severely compromising occupant head protection. Because the SRS uses a dual-stage deployment circuit, this DTC typically triggers a circuit resistance warning. Read the live data stream with a dedicated diagnostic tool to confirm the exact resistance value.
B1705-00›
This DTC indicates the Supplemental Restraint System (SRS) detects a short to ground in the left curtain airbag deployment circuit. Specifically, during self-diagnostics or monitoring, the SRS control module (ACU) detects insulation resistance between the left curtain airbag igniter circuit and vehicle ground (GND) below the system threshold (typically <2Ω). This causes abnormal current leakage to ground instead of normal flow through the airbag deployment circuit. This fault may result in: 1) the left curtain airbag failing to deploy normally in a collision, compromising head protection for front and rear left occupants; 2) the SRS entering fail-safe mode, disabling related airbag functions, and illuminating the instrument cluster airbag warning light; 3) unintended airbag deployment in extreme cases due to abnormal circuit heating. The fault involves the left curtain airbag module, wiring harness, connectors, or internal SRS control module circuits.
B1705›
DTC B1705 indicates the airbag control module (SRS ECU) detects a short to ground in the left curtain shield airbag ignition circuit. During self-diagnostics or real-time monitoring, the ECU detects the insulation resistance between the left curtain airbag ignition line (typically designated as pins FL- or F5) and body ground falls below the threshold (typically <2Ω). This indicates a short-to-ground path in the ignition circuit, which may cause: 1) Curtain airbag fails to deploy during a collision (current shorts to ground and cannot ignite the gas generator). 2) Risk of unintended curtain airbag deployment under abnormal conditions (intermittent poor contact at the short point generates sparks). This constitutes a hard fault in the active safety system. The ECU immediately illuminates the SRS warning light and disables the entire airbag system (including driver, passenger, and side airbags), eliminating side-impact protection.
B170511›
This DTC indicates a short to body ground in the Left Curtain Shield Airbag ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, B170511 constitutes a critical safety fault, indicating an abnormally low-resistance path (typically <1Ω) in the wiring from the Airbag Control Unit (ACU) to the left curtain airbag igniter. The left curtain shield airbag mounts above the driver's side headliner, extending from the A-pillar to the C-pillar. A short to ground results in the following: 1) The curtain airbag fails to deploy normally during a collision (ignition current diverts to the vehicle body); 2) The ACU continuously detects abnormal circuit resistance, illuminates the airbag warning light, and disables the entire SRS; 3) Unintended deployment occurs in extreme cases due to momentary circuit energization. This fault involves a pyrotechnic device ignition circuit (trigger current approx. 1.5-2A, pulse voltage approx. 24-30V). Strictly follow high-voltage safety procedures. Disconnect the battery and wait for the capacitors to discharge before repairing.
B1706-00›
This DTC indicates the Airbag Control Unit (ACU) detects an abnormal short circuit between the ignition drive circuit of the Left Side Curtain Airbag (located inside the driver-side roof side rail) and the vehicle constant power supply (B+). Under normal conditions, the ACU internal boost circuit supplies a high-voltage pulse to the airbag ignition circuit only at the moment of deployment, and the circuit remains insulated from body ground and power lines. When the diagnostic system detects a continuous 12V battery voltage in this circuit, it identifies a short to power. This fault causes the ACU to trigger primary/secondary safety protection and disable the left curtain airbag circuit to prevent accidental deployment, resulting in a loss of head protection during a side-impact collision. If the short-circuit current reaches the deployment threshold, extreme cases may cause unexpected airbag deployment, constituting a severe safety defect.
B1706›
DTC B1706 indicates the SRS (Supplemental Restraint System) detected abnormal continuity between the left curtain airbag (CAB) driver circuit and the vehicle battery positive (B+). This "short to power" means at least one of the two wires in the CAB deployment circuit (typically the high-side and low-side driver wires) is shorted to the 12V power supply, or the squib inside the CAB module has an internal short circuit. The SRS ECU continuously monitors the CAB circuit resistance (normally 2-3 Ω) via its internal diagnostic circuit. If the ECU detects an abnormally high voltage (approaching battery voltage) or abnormal resistance, it immediately sets this DTC and illuminates the airbag warning lamp. Because a short circuit can cause unintended CAB deployment or prevent deployment during a collision, the system enters fail-safe mode and disables the left CAB. This severely compromises occupant head protection during a side impact.
B170612›
DTC B170612 indicates the Airbag Control Module (ACM) detects abnormal continuity between the left curtain shield airbag squib circuit and the vehicle power supply (B+). In the SRS system, the squib remains isolated from the power supply during normal operation. The ACM provides a brief pulse current only at the moment of deployment. A short to power continuously energizes the circuit, resulting in the following: (1) The curtain airbag fails to deploy during a collision, resulting in a loss of side protection. (2) Short-circuit current may damage the internal ACM driver circuit. (3) The system enters fault protection mode, continuously illuminates the instrument cluster SRS warning light, and may sound a buzzer on some models. This fault constitutes a hard short and typically does not clear automatically. Repair immediately.
B1708-00›
BYD defines DTC B1708-00 as "Seat Driver Recline Rearward Switch Circuit Short To Ground", a body electrical system fault. This fault indicates the Seat Control Unit (SCU) detects an abnormal 0-ohm resistance (short to ground) in the driver seat recline rearward switch circuit. Possible causes include switch contacts stuck closed, damaged harness insulation causing a short to ground, or connector water ingress. This fault prevents rearward seat adjustment, causes uncontrolled continuous rearward movement, or disables the seat memory function. Some third-party data sources incorrectly label this code as "left curtain airbag resistance is 0". Airbag faults typically use the B10XX-B19XX range or dedicated SRS fault codes, and standard OBD-II assigns B1708 to the seat adjustment circuit.
B1708›
DTC B1708 indicates the airbag control unit (SRS ECU) detects a 0-ohm resistance in the left side curtain airbag ignition circuit. This typically indicates a short circuit in the ignition circuit (short to ground or short between positive and negative terminals). Under normal operating conditions, the airbag igniter resistance must measure between 2.0 and 3.0 ohms to generate sufficient Joule heat to trigger the gas generator during a collision. A 0-ohm reading means the circuit has virtually no resistance. Potential causes include an internal short circuit in the curtain airbag igniter, wiring harness damage causing direct contact between positive and negative terminals, connector water ingress and corrosion, or a fault in the SRS ECU internal detection circuit. This fault prevents the left side curtain airbag from deploying normally during a side impact (current bypasses the igniter) or, in extreme cases, creates a risk of unintended deployment. This critical fault severely compromises passive safety functions.
B17081A›
DTC B17081A indicates the LHS Curtain Shield Airbag ignition circuit resistance is 0 ohms, representing a short circuit. In the BYD SRS (Supplemental Restraint System), normal curtain airbag inflator resistance is 1.8-2.5 Ω. A 0 Ω resistance indicates a short to ground in the ignition wiring between the SRS control unit and the LHS curtain airbag, or an internal short circuit within the inflator. This fault prevents the LHS curtain airbag from deploying during a collision. The control unit disables the shorted circuit to prevent accidental deployment and illuminates the airbag warning lamp. The short circuit can trigger a protective lockout of the SRS control unit, which in severe cases affects the normal operation of the entire airbag system.
B1709-00›
DTC B1709-00 indicates the resistance of the LH Side Curtain Airbag (also known as the head side airbag) squib circuit falls below the normal threshold set by the SRS ECU (typically below 1.0Ω). The standard airbag squib resistance normally ranges from 1.5Ω to 3.0Ω. Low resistance essentially indicates a short circuit. An internal squib short, a wiring harness short to ground, a short between connector terminals, or a faulty SRS ECU internal detection circuit can cause this condition. This fault causes the airbag control unit to detect an abnormal circuit, illuminate the SRS warning lamp continuously, and potentially activate the system protection mechanism (disabling the LH side curtain airbag and related airbags). In extreme cases, the short circuit can cause unintended airbag deployment in non-collision conditions (though unlikely due to the SRS ECU dual trigger logic). Alternatively, current shunting can prevent proper airbag deployment during a side impact, severely compromising occupant head safety.
B1709›
DTC B1709 indicates the left side curtain airbag (located at the top left of the vehicle, protecting front and rear occupant heads during side impacts) igniter circuit resistance falls below the SRS control unit threshold. (Standard resistance is typically 2.0–3.0 Ω; "low resistance" generally indicates a measured value below 1.5 Ω or near 0 Ω.) This indicates a short in the igniter circuit. Possible causes include a shorted internal squib, a wiring harness short to ground, a wire-to-wire short, or an internal connector short. This fault forces the SRS system into a degraded mode: during a collision, the left side curtain airbag may fail to deploy (loss of protection), or in extreme cases, deploy unintentionally. The system illuminates the airbag warning lamp to indicate an occupant safety system hazard, requiring immediate repair.
B17091A›
DTC B17091A indicates the airbag control unit (SRS ECU) detects the resistance of the left-hand curtain shield airbag igniter circuit is below the system calibration threshold (typically below 1.5Ω; standard operating range is 1.5-3.0Ω). An internal short circuit in the curtain airbag igniter, a wiring harness short to ground, or shorted connector terminals can cause this low-resistance fault in the igniter circuit. After the SRS system enters fail-safe mode, the left-hand curtain shield airbag may fail to deploy during a side impact, posing a severe safety risk.
B170A-00›
DTC B170A-00 indicates the Supplemental Restraint System (SRS) detected the resistance in the left curtain shield airbag igniter circuit exceeds the calibrated threshold (normal range is typically 2.0-3.0Ω; fault threshold is generally >3.5Ω or open circuit). The SRS ECU continuously monitors the circuit impedance of each airbag igniter using a low-current detection circuit. Excessive resistance indicates a high-resistance condition in the circuit. Potential causes include poor connector contact, a partially broken wiring harness, or increased internal resistance from igniter aging. This fault prevents the left curtain shield airbag from deploying normally during a collision and constitutes a critical failure in the passive safety system.
B170A›
DTC B170A indicates the Left Side Curtain Airbag ignition circuit resistance exceeds the normal threshold set by the SRS control unit (typically >3.0 Ω, standard range 1.5–2.5 Ω). This Level 2 airbag system fault means the Left Side Curtain Airbag may fail to deploy normally or experience delayed deployment during a collision, severely compromising side-impact occupant protection. High resistance typically indicates a high-impedance point in the circuit, such as a partially broken wire, increased connector contact resistance, oxidation, corrosion, or an internal open circuit in the airbag inflator. The SRS control unit continuously monitors this circuit. Upon detecting abnormal resistance, the unit illuminates the airbag fault warning lamp and may disable the entire airbag system to prevent accidental deployment.
B170A1B›
This DTC indicates the Supplemental Restraint System (SRS) detected the igniter (squib) circuit resistance of the left curtain shield airbag (located above the driver-side window between the B-pillar and C-pillar) exceeds the calibrated threshold (typically >3.6Ω, normal range 1.5-3.0Ω). Excessive resistance usually indicates a high-resistance connection, a partial open circuit, poor connector contact, or an internal open circuit in the igniter. This fault may prevent the left curtain shield airbag from deploying during a side impact and continuously illuminates the SRS warning light. This is a critical fault affecting passive safety.
B170D-00›
This DTC indicates the SRS (Supplemental Restraint System) control module detects a disconnected right side curtain airbag or interrupted communication. When the ignition switch is ON, the SRS module monitors the airbag inflator circuit resistance (normal range: 2.0-4.0 Ω) to verify the airbag module's presence. If the SRS module detects an open circuit (infinite resistance), a resistance value exceeding the threshold (>10 Ω), or a loss of communication, it flags the airbag as "not connected". Potential causes include an open airbag wiring harness, a loose connector, oxidized or corroded terminals, an internal open circuit in the airbag module, or a failed internal diagnostic circuit in the SRS control module. This fault eliminates right-side head protection during a side impact or rollover. As a critical passive safety system fault, it requires immediate repair.
B170D›
DTC B170D indicates the SRS (Supplemental Restraint System) control unit detects an open circuit or disconnection in the right-hand (RH) curtain airbag circuit. Specifically, during the self-test, the control unit fails to detect the load signal from the RH curtain airbag inflator within the specified time (typically under 6 seconds). Normal resistance is 1.6-2.4Ω. This fault prevents the RH curtain airbag from deploying during a side impact or rollover accident, severely compromising occupant head protection, and continuously illuminates the instrument panel SRS warning light. Determine whether the cause is a loose harness connector, an open circuit in the wiring, or a faulty curtain airbag module.
B170D1B›
This DTC indicates the SRS (Supplemental Restraint System) control module detects an open circuit in the Curtain Shield Airbag RH ignition circuit. Specifically, the ACU (Airbag Control Unit) continuously monitors the circuit resistance of each airbag inflator. When the Curtain Shield Airbag RH resistance exceeds the normal range (typically >10Ω or infinite), the ACU registers a 'disconnected' state. This fault prevents the Curtain Shield Airbag RH from deploying during a side impact or rollover, severely compromising occupant head protection, and continuously illuminates the instrument cluster airbag fault warning lamp.
B170E-00›
DTC B170E-00 indicates an abnormally low-resistance connection between the Right Side Curtain Airbag squib circuit and body ground (GND). In the SRS (Supplemental Restraint System) architecture, two independent wires connect each airbag inflator to the ACU (Airbag Control Unit). Normal resistance typically ranges from 1.5 to 3.0 Ω. The ECU identifies a short to ground when it detects circuit resistance below the threshold (typically <1.0 Ω) or abnormal voltage to ground. This fault causes: 1) The Right Side Curtain Airbag to fail to deploy properly in a collision, resulting in loss of side-impact protection. 2) The SRS to enter fail-safe mode, keeping the instrument cluster airbag warning lamp illuminated and degrading the vehicle safety rating. 3) A risk of unintended deployment in extreme cases due to intermittent wiring contact. This is a passive safety system hard fault and requires immediate resolution.
B170E›
DTC B170E indicates the SRS (Supplemental Restraint System) control unit detects a short to body ground in the right curtain shield airbag ignition circuit. Specifically, the ACU detects the resistance between the right curtain airbag deployment circuit (typically marked R CSA+ and R CSA-) and ground falls below the threshold (generally <2Ω). Damaged wiring harness insulation, connector water ingress and corrosion, a shorted inflator inside the curtain airbag module, or a driver transistor breakdown inside the SRS control unit can cause this fault. Under this fault condition, the circuit protection mechanism may disable the curtain airbag (preventing deployment). In extreme cases, short-circuit current can trigger unintended deployment, posing a severe safety hazard.
B170E11›
B170E11 indicates a short to ground in the ignition circuit of the right side curtain airbag. In the BYD SRS (Supplemental Restraint System) architecture, this fault code indicates the airbag control unit (ACU) detects an abnormally low-resistance path between the right side curtain airbag squib wiring and vehicle body ground (typically below the 1.5-2.0 ohm threshold). This short circuit causes the ACU to determine the curtain airbag cannot deploy normally, triggering fail-safe mode. The instrument panel airbag warning light illuminates continuously, and the system suspends deployment control for this curtain airbag. Consequently, the right side curtain airbag may fail to activate during a side collision, severely compromising crash protection for right-side occupants, particularly head protection. Potential causes include damaged wiring harness insulation, connector water ingress and corrosion, an internal short circuit in the clock spring, or a squib failure within the curtain airbag module itself.
B170F-00›
DTC B170F-00 indicates a short to power fault in the driver seat Occupant Sensing System (OSS). Integrated into the driver seat cushion, the sensor uses a pressure sensing mat and an electronic control module to detect seat occupancy. It sends a 0.4-4.6V analog voltage signal to the SRS airbag control unit (approximately 0.5V when unoccupied and 4.2V when occupied). The SRS module sets this DTC when it detects a continuous voltage above 4.8V or near battery voltage. This occurs if the signal circuit shorts to the 12V power supply line (B+), the internal sensor circuit breaks down, or the control module fails. This fault forces the SRS system into fail-safe mode: the driver airbag may fail to deploy, the seat belt reminder function may malfunction (false or missing warnings), and the instrument cluster airbag warning light remains illuminated. Because this fault affects the passive safety system, do not drive the vehicle until repaired.
B170F›
DTC B170F indicates a short to power (B+) in the right-hand curtain airbag (SRS Curtain Shield Airbag - RH) ignition circuit. In the BYD SRS system, the curtain airbag uses an electrically ignited gas generator. During normal operation, the control unit supplies a momentary high current to trigger ignition. The diagnostic system triggers this fault when it detects abnormal continuity (resistance below the threshold, typically <10Ω) between the curtain airbag ignition circuit and the vehicle power supply (12V battery positive terminal), or when the circuit voltage remains above the set value (approximately 5V). This is a hard fault. The SRS control unit immediately disables the right-hand curtain airbag function and illuminates the instrument cluster airbag warning lamp. Potential risks include: 1) The right-hand curtain airbag fails to deploy in a collision, resulting in a loss of occupant head protection. 2) In extreme cases, if the short circuit contact resistance fluctuates, vehicle jolts can generate a momentary current, creating a minimal risk of unintended curtain airbag deployment. Therefore, the system classifies this as a severe fault and prohibits continued vehicle operation.
B170F12›
DTC B170F12 indicates a short to power in the right side curtain airbag ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, this fault indicates the airbag control unit (ACU) detects an abnormally low-impedance connection between the right side curtain airbag igniter circuit (typically two wires: high-side driver and low-side driver) and the vehicle power supply (+12V or +B). This hardware short-to-battery fault may cause: 1) risk of unintended airbag deployment (in extreme cases); 2) airbag failure to deploy during a collision; 3) the SRS entering protection mode, disabling related airbag functions. The '12' suffix in the BYD diagnostic protocol typically designates the specific 'short to power' subtype.
B1712-00›
This DTC indicates the RH Curtain Shield Airbag igniter circuit resistance measures 0 Ω, indicating a typical short circuit. Normal airbag igniter resistance is 2.0-5.0 Ω. A 0 Ω resistance typically indicates a short to ground in the igniter circuit (damaged harness insulation), a short to power (contact with constant power), or a shorted driver transistor inside the airbag control module (SRS ECU). This fault forces the SRS system into fail-safe mode: the affected airbag will not deploy during a collision (the short circuit diverts the deployment current), and the airbag warning lamp illuminates continuously. Some models simultaneously disable the front seat belt pretensioners and the corresponding side airbag. The short circuit also carries a minimal risk of unintended deployment. Immediately remove the vehicle from service for repair.
B1712›
DTC B1712 indicates the SRS (Supplemental Restraint System) detects a 0 ohm resistance in the right curtain airbag firing circuit (located in the roof side rail, protecting front and rear occupant heads). This indicates a hard short circuit in the firing circuit (short to ground or short to power), not an open circuit. Normal airbag inflator resistance ranges from 2.0-3.0 ohms (typical value approx. 2.3Ω). A 0 ohm resistance allows current to bypass the inflator bridge wire. This prevents proper airbag deployment during a collision or creates a major safety risk of unintended deployment. The SRS ECU continuously monitors all firing circuit impedances in real time using a highly sensitive Wheatstone bridge circuit. If the ECU detects a resistance below the safety threshold (typically <0.8Ω), it sets this DTC, illuminates the airbag warning light, immediately disables the right curtain airbag and related coordinated protection strategies, and enters safety protection mode.
B17121A›
DTC B17121A indicates the Supplemental Restraint System (SRS) detects a 0-ohm resistance in the right curtain airbag ignition circuit. Under normal operating conditions, the curtain airbag squib requires a specific resistance (typically 2.0–3.0 ohms, depending on the vehicle model). A 0-ohm resistance indicates a short circuit. Possible causes include an internal short in the curtain airbag module, a short between the positive and negative harness wires, or a short between connector terminals. This fault causes the SRS control unit to determine the curtain airbag has deployed or has a circuit fault. Consequently, the right curtain airbag fails to deploy during a collision. This severely compromises side impact protection and constitutes a high-risk safety fault.
B1713-00›
DTC B1713-00 indicates the airbag control unit (SRS ECU) detects the right curtain shield airbag ignition circuit resistance falls below the system-calibrated minimum threshold (typically below 1.0Ω; normal range is 1.5-3.0Ω). Low resistance usually indicates an abnormally low-resistance path in the ignition circuit. Possible causes include an internal inflator short circuit within the curtain airbag module, a wiring harness short to ground, grounded internal connector pins, or a wire-to-wire short. This fault prevents normal airbag deployment (failure to inflate during a collision) or, in extreme cases, creates a risk of unintended deployment. This critical occupant safety fault requires immediate repair.
B1713›
DTC B1713 indicates the right curtain airbag igniter circuit resistance falls below the normal threshold set by the SRS control unit (typically 2.0-5.0Ω). Low resistance (<2Ω or close to 0Ω) indicates a short circuit risk in the igniter circuit. Potential causes include an internal short circuit in the curtain airbag, a wiring harness short to ground, or an abnormal internal driver circuit in the SRS ECU. This fault forces the SRS system into fail-safe mode. During a collision, the right curtain airbag may fail to deploy, or it may deploy unintentionally. This constitutes a high-level safety fault.
B17141B›
DTC B17141B indicates the right curtain airbag ignition circuit resistance exceeds the normal threshold set by the SRS control module (typically 3.0-5.0Ω, depending on vehicle calibration). This active SRS system fault means the right curtain airbag may fail to deploy or experience delayed deployment during a collision. Excessive resistance usually indicates a high-resistance point in the ignition circuit. Potential causes include poor wiring contact, connector oxidation or corrosion, a partially broken wiring harness, or an internal open circuit in the curtain airbag module. This fault illuminates the SRS warning light continuously and forces the system into degraded mode. Extreme cases may compromise side-impact protection.
B17131A›
DTC B17131A indicates the RHS Curtain Shield Airbag squib circuit resistance falls below the normal threshold calibrated by the SRS control module (typical standard value: 2.0 ± 0.5 Ω). This fault signifies a partial circuit short, an internal component short, or a wiring insulation failure to ground, dropping circuit resistance below approximately 1.5 Ω. This condition triggers the airbag system fail-safe mechanism. Low resistance can prevent proper curtain airbag deployment during a collision, as the short circuit diverts ignition energy. Furthermore, a severe short circuit increases the risk of unintended deployment. The SRS typically disables the affected curtain airbag circuit, eliminating occupant head protection during a side impact. This safety hazard requires immediate repair.
B1714-00›
DTC B1714-00 indicates the airbag control unit (SRS ECU) detects the circuit resistance of the RH Curtain Shield Airbag inflator (gas generator) exceeds the calibrated threshold. The normal range is typically 1.5Ω–2.5Ω; an excessive value generally indicates >3.5Ω or a near open circuit. The SRS ECU periodically measures this resistance using a low-current signal. Increased resistance indicates poor circuit contact, wiring oxidation, a partially broken wiring harness, or an aging/broken bridge wire inside the inflator. This fault may prevent the RH Curtain Shield Airbag from deploying properly during a collision, degrading passive safety system function. The SRS warning lamp illuminates continuously and the system enters fail-safe mode (which may disable this circuit's trigger function to prevent unintended deployment).
B1714›
DTC B1714 indicates the SRS (Supplemental Restraint System) control unit detects the right curtain airbag (head protection curtain/side curtain) inflator circuit resistance remains above the calibrated threshold (normal range typically 1.5-3.5 Ω, depending on vehicle calibration). The SRS ECU periodically monitors each airbag inflator's resistance via an internal Wheatstone bridge or constant-current source circuit. Excessive resistance indicates a high-impedance point in the inflator circuit. Potential causes include poor connector contact, a partial open circuit in the wiring harness, or an aging inflator. This constitutes a hard or intermittent fault. During a side impact, the right curtain airbag may fail to deploy within the specified time (delayed deployment) or fail to deploy entirely. The system illuminates the airbag warning light, and the front side airbags and seat belt pretensioners may enter fail-safe mode.
B1717-00›
This DTC indicates the SRS (Supplemental Restraint System) ECU detected an open circuit or disconnected condition in the left knee airbag module (Driver Knee Airbag Module) during self-diagnosis. Specifically, when the SRS ECU sends a test signal to the left knee airbag igniter circuit, it fails to receive a normal circuit response or detects a circuit resistance exceeding the normal threshold (typically infinite or extremely high resistance). Consequently, the left knee airbag may fail to deploy during a collision, resulting in a loss of lower limb protection for the driver. Additionally, the SRS enters fail-safe mode and continuously illuminates the instrument cluster airbag warning light. The system may also lock the deployment function of the entire airbag system, severely compromising passive safety performance.
B1717›
DTC B1717 indicates a loss of communication or an open circuit between the driver-side knee airbag and the SRS (Supplemental Restraint System) control unit. Specifically, this fault indicates an incorrect connection at the knee airbag module located under the left side of the dashboard, an open circuit in the wiring, or an internal open circuit in the airbag squib. The knee airbag, a critical component of the frontal impact protection system, limits the forward movement of the driver's lower limbs and distributes crash forces. When this fault occurs, the SRS control unit illuminates the airbag warning light and may enter fail-safe mode, disabling the related airbag circuit to prevent accidental deployment. Consequently, the knee airbag will fail to deploy during a collision, increasing the risk of lower limb injury to the driver.
B17171B›
DTC B17171B indicates the SRS (Supplemental Restraint System) control module detects an open circuit in the left knee airbag (Driver Knee Airbag) igniter circuit. The resistance value falls outside the normal range (normal: approx. 2-3Ω; open circuit: >10Ω or infinite). This fault indicates a physical break in the wiring or connector between the airbag ECU and the left knee airbag assembly, or an internal open circuit within the airbag igniter itself. The knee airbag protects the driver's lower limbs from dashboard intrusion during a frontal collision. This fault prevents the airbag from deploying during a crash and may trigger the SRS secondary protection mechanism (e.g., disabling the associated airbag group), posing a severe safety hazard. In the BYD diagnostic protocol, the '1B' suffix specifically denotes an 'open circuit/high resistance' condition.
B1718-00›
B1718-00 indicates a short to ground in the driver-side knee airbag ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, this fault code indicates the airbag control module (ACM) detects the left knee airbag inflator circuit resistance is below the threshold (typically < 1.0Ω), identifying a short to ground. This fault forces the entire airbag system into fail-safe mode and continuously illuminates the instrument cluster SRS warning lamp. During a collision, the knee airbag may fail to deploy, and the fault may affect the deployment strategy for other front airbags. This constitutes a hard fault. Once confirmed, it remains active; cycling the ignition does not clear it.
B1718›
B1718 is a BYD-specific SRS (Supplemental Restraint System / airbag system) fault code indicating an unintended low-resistance path (short to ground) between the driver-side knee airbag (Left Knee Airbag) ignition circuit and vehicle ground (GND). The knee airbag contains an igniter (squib). Under normal conditions, both igniter terminals must show an open circuit (infinite resistance) to ground. A short to ground indicates current may bypass the igniter and flow directly to ground, causing the airbag control unit (ACU) to register a fault in that airbag circuit. This fault poses a severe safety risk. The short circuit can prevent the airbag from deploying during a collision or, in extreme cases, trigger unintended deployment. The system classifies this fault as severity level 3, illuminates the SRS warning lamp continuously, and may force the entire airbag system into fail-safe mode (disabling all airbags).
B1719-00›
DTC B1719-00 indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance connection (short circuit) between the Driver Knee Airbag squib circuit and the vehicle power supply (B+). Under normal operating conditions, the airbag squib circuit exhibits high resistance (2-5 Ω) and lacks continuity to power or ground. A short to power causes the SRS ECU to detect an abnormally high circuit voltage (close to 12 V) and register a severe fault. This condition may prevent the airbag from deploying correctly during a collision (as the short circuit bypasses the current) or, in extreme cases, cause unintended deployment (though a short circuit typically prevents rather than triggers ignition). Repair this critical safety fault immediately.
B171811›
DTC B171811 indicates an abnormally low-resistance connection (typically <1.5Ω) between the Driver Knee Airbag squib circuit and the vehicle chassis ground (GND). In the SRS (Supplemental Restraint System), the squib circuit must maintain a high-impedance state (normally 2-3Ω). The airbag control unit (ACU) logs a short to ground when it detects circuit resistance continuously below the threshold or abnormal current flow to ground. This fault forces the ACU into an immediate fail-safe mode, disabling the knee airbag and potentially related airbag systems, and illuminates the instrument cluster airbag warning light. Potential causes for this short to ground include contact between the internal squib bridge wire and the housing, damaged harness insulation shorting to the chassis, bent connector terminals touching metal components, or a breakdown of the internal ACU driver circuit. This creates a dual safety risk of unintended airbag deployment (premature deployment) or failure to deploy during a collision. Technicians must repair this hard fault immediately.
B1719›
DTC B1719 indicates a short to B+ in the Driver Side Knee Airbag squib circuit. In the SRS (Supplemental Restraint System) architecture, the knee airbag squib is a low-value resistor (standard value 2.0 ± 0.3 Ω). Under normal conditions, the airbag ECU triggers the squib by controlling the ground circuit. When the diagnostic system detects the circuit voltage continuously exceeding the threshold (typically above 4.5V, approaching the 12V battery voltage), it identifies a short to power. This fault results in the following: 1) The ECU actively disables the airbag circuit, preventing deployment during a collision and resulting in a loss of driver leg protection. 2) A potential safety risk exists; in extreme cases, circuit abnormalities may cause unintended airbag deployment. 3) The SRS enters fail-safe mode and continuously illuminates the instrument cluster airbag warning light. Inspect for damaged wiring harness insulation, misaligned connector terminals, electrolytic short circuits caused by fluid ingress, and internal short circuits within the airbag module squib.
B171912›
DTC B171912 indicates a short to the 12V power supply in the driver-side knee airbag igniter circuit. In the BYD SRS system, the normal resistance of the airbag igniter is 2.0 ± 0.3 Ω. The Airbag Control Unit (ACU) continuously monitors this resistance through a low-current diagnostic circuit. A "short to power" means the signal wire or return wire in the igniter circuit shorts to the vehicle constant power (B+), causing circuit resistance to rise abnormally (approaching infinity or exhibiting short-circuit characteristics). This fault is extremely dangerous. It can cause the airbag to deploy unexpectedly while driving, injuring occupants. Alternatively, during a collision, the ACU may detect the circuit fault and fail to trigger the airbag, disabling the protection function. Upon detecting this fault, the ACU immediately illuminates the instrument cluster SRS warning light and locks the airbag system into fail-safe mode.
B2AB049›
DTC B2AB049 indicates a malfunction in the current sampling circuit of the electric compressor drive controller in the thermal management system. This circuit typically uses a Hall effect sensor or a precision shunt resistor to monitor the compressor motor operating current in real time, enabling overcurrent protection, closed-loop torque control, and stall detection. The controller sets this fault when it detects a sampled value outside the valid range (e.g., signal line open circuit, short to ground or power, sampled value continuously at zero or saturated, or an abnormal three-phase current vector sum). When this fault occurs, the compressor initiates a protective shutdown, disabling the air conditioning cooling and heating functions. If the vehicle uses a heat pump system or relies on the air conditioning system for battery cooling, prolonged operation may overheat the battery or motor, but generally does not directly affect driving safety.
B171C-00›
DTC B171C-00 indicates the driver's knee airbag circuit resistance is 0 Ω, representing a hard short. In the SRS (Supplemental Restraint System), normal airbag squib resistance is 2.0-3.0 Ω. A 0 Ω reading indicates a line short to ground between the SRS ECU and the knee airbag, an internal short in the airbag squib, or a short caused by abnormal connector terminal contact. This fault triggers the SRS fail-safe mode. The airbag may fail to deploy during a collision, or in extreme cases, the wiring fault could cause unintended deployment (a low-probability theoretical risk). Because the knee airbag sits in front of the driver's knees (beneath the dashboard), water ingress, physical impacts, or aftermarket modifications easily affect this area. Consequently, it is one of the SRS components most prone to short circuits.
B171C›
DTC B171C indicates the Airbag Control Unit (ACU) detects 0 ohms in the Driver Side Knee Airbag igniter circuit. This points to a short to ground in the circuit or an internal short in the igniter. In the BYD SRS system, normal airbag igniter resistance is 2.0-5.0Ω. When the ACU detects circuit resistance below the threshold (typically <0.8Ω), it registers a short circuit fault, illuminates the airbag warning lamp, and disables the airbag to prevent accidental deployment. During a frontal collision, the driver loses knee airbag protection, risking severe lower limb injury. This fault does not cause unintended airbag deployment.
B171C1A›
DTC B171C1A indicates the Supplemental Restraint System (SRS) detects a 0Ω resistance in the Driver Knee Airbag ignition circuit, representing a typical short circuit fault. Normal airbag inflator resistance measures between 2.0 and 3.0Ω. A 0Ω resistance indicates a Line Short to Ground in the ignition circuit. Possible causes include an internal short circuit in the airbag module, damaged wiring harness insulation grounding to the chassis, or a short circuit between connector terminals. This fault causes the SRS control unit to flag the left knee airbag as unavailable, preventing deployment during a collision. The control unit also illuminates the airbag warning light continuously. The knee airbag is a critical restraint system component that protects the driver's lower limbs from dashboard intrusion. Consequently, this fault significantly reduces protection performance during a frontal collision.
B171D-00›
DTC B171D-00 indicates the resistance of the driver-side left knee airbag ignition circuit is below the normal threshold set by the SRS control unit (typically below 1.5Ω; the standard value is 1.6-2.4Ω). This fault indicates a short circuit in the knee airbag ignition circuit. Potential causes include an internal short in the airbag igniter coil, damaged wiring insulation causing a short between positive and negative circuits, or a short between connector terminals. The SRS system identifies the airbag circuit as abnormal. The knee airbag may fail to deploy during a collision or, in extreme cases, deploy unintentionally. Consequently, the system illuminates the airbag warning light and logs this fault code.
B171D›
DTC B171D indicates the driver-side knee airbag igniter circuit resistance falls below the lower threshold calibrated by the SRS control unit (ACU), typically under 2.0 Ω. In the BYD SRS system, the knee airbag serves as a critical restraint system component, with a standard igniter resistance range of 2.0–3.0 Ω. A low resistance value indicates a short circuit risk. Potential causes include an internal short in the igniter assembly, a short between wiring harness connector pins, or a wiring harness short to ground or power. This fault causes the ACU to classify the airbag circuit as unsafe. During a collision, the knee airbag may fail to deploy, or in extreme cases, deploy unintentionally. Consequently, the SRS system illuminates the airbag fault warning lamp and may disable the entire airbag system.
B171D1A›
This DTC indicates the driver-side knee airbag module squib resistance falls below the SRS control unit (ACU) threshold (typically below 1.5Ω). The knee airbag mounts on the left side of the dashboard below the steering wheel to protect the driver's knees and lower limbs during a frontal collision. Low resistance typically indicates a short circuit in the squib circuit (short between wires, short to ground, or internal short within the airbag module), causing the ACU to detect abnormally low circuit resistance. This fault forces the SRS system into degraded mode. During a collision, the knee airbag may fail to deploy or deploy inadvertently. Simultaneously, the instrument cluster airbag warning light remains illuminated, severely compromising passive safety functions.
B171E-00›
DTC B171E-00 indicates the driver-side knee airbag ignition circuit resistance exceeds the normal threshold range (typically 1.5Ω-3.5Ω, depending on vehicle calibration) established by the SRS control module (ACU), registering as excessively high resistance. Potential causes include increased internal resistance in the airbag inflator, poor wiring harness connector contact, a wiring harness open or short circuit, or a faulty internal sampling circuit within the control module. This fault forces the SRS system into a degraded mode and illuminates the instrument panel airbag warning light. During a collision, the knee airbag may fail to deploy, compromising lower limb protection for the driver.
B171E›
DTC B171E indicates the driver-side knee airbag (Left Knee Airbag Module) firing circuit resistance exceeds the ACU (Airbag Control Unit) calibrated threshold (typically >3.0Ω, standard value 2.0-3.0Ω). Located under the left side of the dashboard, this airbag protects the driver's lower limbs from secondary impact during a frontal collision. High resistance essentially indicates an open circuit or high-impedance state. Causes include poor airbag connector contact, an open wiring harness inside the dashboard, an internal open circuit in the airbag inflator, or an ACU detection circuit fault. This fault forces the SRS system into fail-safe mode. It can prevent the knee airbag from deploying during a collision, continuously illuminate the instrument panel airbag warning light, and compromise the vehicle's passive safety system.
B171E1B›
This fault code indicates the airbag control unit (SRS ECU) detects the left knee airbag (Driver Knee Airbag) igniter circuit resistance exceeds the calibrated upper limit (typically >3.5Ω; normal range is 2.0-3.0Ω). Excessive resistance indicates a high-resistance point in the igniter circuit. Potential causes include poor connector contact, a partially broken wiring harness, oxidation, or an aging spiral resistance wire inside the airbag module. This fault forces the SRS system into a degraded protection mode, and the left knee airbag may fail to deploy during a collision (this airbag protects the driver’s lower limbs from rearward steering column movement or instrument panel intrusion). The airbag warning light remains illuminated on the instrument panel, and some models trigger a warning buzzer. Because this fault affects a core passive safety system function, it presents a safety risk and requires immediate inspection.
B1721-00›
B1721-00 is a BYD SRS (Supplemental Restraint System) fault code indicating a communication interruption or open circuit between the front passenger (right) knee airbag and the Airbag Control Unit (ACU). The fault triggers when the ACU detects the right knee airbag deployment circuit resistance falls outside the normal range (typically 2.0Ω-3.0Ω), causing the system to register a 'not connected' state. During a collision, the right knee airbag may fail to deploy, leaving the front passenger's knees and lower limbs unprotected. Additionally, the SRS fail-safe mechanism may force the entire airbag system into a degraded mode, affecting the normal operating logic of other airbags.
B17211B›
DTC B17211B indicates the Supplemental Restraint System (SRS) detects a communication loss or abnormal resistance between the right knee airbag (typically located under the passenger-side dashboard) and the SRS control module. Specifically, this fault indicates an open airbag igniter circuit (resistance too high, typically >10Ω), which the system registers as a "not connected" state. This condition prevents the right knee airbag from deploying during a collision and continuously illuminates the airbag fault warning lamp. This constitutes a hard fault or intermittent open circuit requiring immediate repair to ensure passive safety system integrity.
B1722-00›
DTC B1722-00 indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance connection to body ground (short to ground) in the right knee airbag (front passenger side knee airbag) squib circuit. The knee airbag contains a gas generator electrothermal igniter (typical resistance 2 ± 0.5 Ω). The SRS module determines circuit integrity by monitoring circuit current and resistance. If damaged wiring harness insulation contacts vehicle body metal, water enters the connector causing a short between terminals, or the internal airbag module igniter shorts, circuit resistance drops to nearly 0 Ω. The control unit immediately cuts power to the circuit and illuminates the airbag fault warning lamp to prevent unintended airbag deployment or insufficient ignition energy. In this condition, the right knee airbag fails to deploy during a collision, and the entire SRS system may enter a degraded protection mode.
B172211›
DTC B172211 indicates the Supplemental Restraint System (SRS) detects an abnormally low-resistance path (short circuit) to body ground in the right knee airbag (passenger-side knee airbag) ignition circuit. Under normal conditions, the airbag igniter circuit resistance should be between 2.0 and 3.0 Ω. The ECU determines a short to ground when it detects circuit resistance below 1.0 Ω or voltage to ground near 0 V. This fault prevents proper airbag deployment during a collision (as the ECU disables the circuit to protect the power supply) or, in extreme cases, causes unintended deployment. Simultaneously, the SRS enters fail-safe mode, illuminates the airbag warning light, and may lock the entire airbag system, severely compromising passive safety performance.
B1723-00›
B1723-00 indicates the Supplemental Restraint System (SRS) detected a short to vehicle power (B+, 12V) in the ignition circuit (squib circuit) of the right knee airbag (passenger-side knee airbag, typically located below the right side of the dashboard). Under normal conditions, the SRS control unit (ACU) maintains a specific voltage across the airbag inflator terminals (typically a 5V or 12V pulse diagnostic voltage), and circuit resistance measures between 2.0 and 3.0 Ω. When the ACU detects the circuit voltage remains at or near battery voltage (>10V), it identifies a short to power. This fault can cause: 1) the right knee airbag to fail to deploy properly during a collision; 2) the SRS to enter fail-safe mode, disabling all airbag functions; 3) a potential risk of unintended airbag deployment. This severe-level fault requires immediate repair.
B1723›
This DTC indicates a short to vehicle power (B+) in the SRS (Supplemental Restraint System) Right Knee Airbag ignition circuit. Under normal operating conditions, the airbag ignition circuit remains isolated from the power supply. The SRS ECU triggers the circuit with a specific current only during a collision. When the control unit detects a short to power in this circuit, it logs a severe fault, immediately illuminates the airbag warning lamp, and enters fail-safe mode. This mode may disable the entire airbag system to prevent accidental deployment or system failure. During a frontal collision, the knee airbag limits the forward movement of the occupant's lower limbs, preventing femur and hip injuries caused by the knees striking the instrument panel. Therefore, this fault directly compromises occupant passive safety protection.
B172312›
DTC B172312 indicates the Supplemental Restraint System (SRS) detects an abnormally low-resistance path between the right knee airbag (Knee Airbag - Passenger Side) ignition circuit and the vehicle positive power supply (+B, usually 12V). In the SRS, normal airbag squib resistance is typically 2-3Ω. The ECU supplies a low-voltage detection signal. When the circuit shorts to power, the ECU detects an abnormally high voltage or a constant 12V and logs a Short to B+ fault. This severe active safety system fault may cause: 1) the airbag to fail to deploy during a collision (the short circuit diverts ignition energy); 2) unexpected airbag deployment in extreme cases due to short-circuit current; 3) the SRS to enter fail-safe mode, restricting all airbag functions. The '12' in the DTC is the sub-code specifically indicating a short-to-power fault.
B1726-00›
DTC B1726-00 indicates the Airbag Control Module (ACM) detects an abnormal resistance of 0 ohms (or below 0.8 Ω) in the Passenger Knee Airbag igniter circuit, evaluating it as a wiring short to ground or an internal short circuit within the airbag module. In BYD Qin series and similar models, this DTC strictly corresponds to the right knee airbag circuit. However, the SRS systems in other models (such as Song Pro, Tang DM-i, and Qin Plus) define this code as a front passenger seat Occupant Classification Sensor (OCS) circuit fault. Regardless of the specific definition, the SRS system detects abnormal circuit impedance in the passenger-side lower safety protection device. This causes the system to enter fault protection mode, disable the airbag deployment function, and illuminate the instrument cluster airbag warning light. A 0-ohm resistance typically indicates a short circuit risk; prevent accidental deployment or complete failure.
B1726›
DTC B1726 indicates the SRS (Supplemental Restraint System) control unit detects a Right Knee Airbag circuit resistance of 0Ω or near 0Ω. Normal airbag inflator resistance is 1.5-3.0Ω. A resistance of 0Ω indicates a short circuit in the airbag circuit. Potential causes include an internal short in the airbag inflator, a wiring harness short to ground, or a short between connector terminals. This fault causes the SRS to enter protection mode. During a collision, the Right Knee Airbag may fail to deploy normally. The system also illuminates the airbag warning light and may disable the entire airbag system to protect occupants.
B17261A›
DTC B17261A indicates the front passenger seat Occupant Classification System (OCS) sensor detects a circuit resistance of 0 or an open circuit. This sensor integrates into the front passenger seat cushion and uses pressure-sensing elements to monitor seat occupancy status in real time (empty/child/adult classification). A resistance of 0 typically indicates a short to ground in the sensor power or signal wire, an internal open circuit, or a disconnected connector. This fault causes the airbag control unit (SDM) to enter degraded mode, preventing it from accurately determining the front passenger type during a collision. The SDM may incorrectly suppress the front passenger frontal and knee airbags, or cause unintended airbag deployment, severely compromising the passive safety system protection strategy.
B1727-00›
This DTC indicates the Airbag Control Unit (ACU) detects the right knee airbag (front passenger knee airbag) squib circuit resistance is below the system calibration threshold (typically <1.0Ω; normal range: 2.0-3.0Ω). Low resistance indicates an abnormally low-resistance path in the circuit. A short to ground, a wire-to-wire short, or an internal short in the airbag squib typically causes this condition. This fault presents two severe risks: first, short-circuit current can trigger unintended airbag deployment, injuring occupants; second, excessive circuit current during a collision can burn the contacts, preventing airbag deployment. This fault constitutes an active safety system failure. The vehicle remains drivable, but the airbag system enters degraded protection mode. During a collision, the right knee airbag and any other airbags with related faults will fail to deploy.
B1727›
DTC B1727 indicates the SRS (Supplemental Restraint System) ECU detects Passenger Knee Airbag squib circuit resistance below the calibrated threshold (typically <1.0Ω or <1.5Ω, depending on vehicle calibration). This fault represents an abnormally low impedance in the squib circuit. Potential causes include an internal short circuit in the squib coil, a wiring harness short to ground, a short between connector terminals, or a faulty internal sampling circuit within the SRS ECU. Low resistance typically indicates an abnormal current path, causing the SRS system to identify a risk of unintended deployment or monitoring failure. The system subsequently illuminates the airbag warning light and may disable the entire airbag system. This results in the loss of knee protection during a collision and disrupts the normal deployment logic of other airbags.
B17271A›
BYD's diagnostic system assigns two definitions to DTC B17271A depending on the vehicle platform. On early ICE platforms like the Qin PRO, the code indicates the right passenger knee airbag ignition circuit resistance falls below the standard threshold (normal range 1.5–3.0 Ω, measured value <1.0 Ω). This indicates a hard short in the circuit, an internal short in the airbag module, or damaged wiring insulation, which may prevent normal airbag deployment or cause unintended deployment without a collision. On newer platforms like e-Platform 3.0 and DM-i, the code indicates a left rear blind spot detection (BSD/BSDA) radar sensor fault. Causes include hardware damage, CAN communication interruption, a power supply short circuit, or loss of system calibration data. Both scenarios constitute a safety-related system failure. The vehicle remains drivable with caution, but safety protection functions operate with limitations. Repair the vehicle immediately.
B1728-00›
DTC B1728-00 indicates the Airbag Control Unit (ACU) detects the squib circuit resistance of the right knee airbag (usually located beneath the passenger-side dashboard) exceeds the calibrated threshold. The normal range is typically 1.5-3.0 Ω, varying by vehicle calibration. High resistance generally means >3.5 Ω or a near open-circuit condition. This is an actively monitored SRS fault. The ACU continuously monitors the airbag squib circuit current and resistance to determine circuit integrity. High resistance indicates a high-resistance connection in the squib circuit. This may result in insufficient ignition energy during a collision, preventing proper airbag deployment. In extreme cases, the system detects an open-circuit fault and triggers a secondary lockout, compromising the entire airbag system operation. This fault illuminates the instrument cluster SRS warning lamp and forces the vehicle passive safety system into a degraded protection mode.
B1728›
DTC B1728 indicates the SRS (Supplemental Restraint System) ECU detects the right knee airbag squib circuit resistance exceeds the calibrated threshold (the normal range is typically 1.5-3.0Ω; actual thresholds vary by vehicle software version, generally triggering this code at >3.5Ω). Electrically, excessive resistance indicates a high-impedance point in the circuit, resulting from increased contact resistance, a partial open circuit, or squib aging. This hard or intermittent fault causes the SRS to enter a degraded mode. During a collision, the airbag may fail to inflate, experience delayed inflation, or deploy with insufficient energy, failing to effectively protect the occupant's knees and lower limbs. Simultaneously, the instrument cluster airbag warning light remains illuminated, and the system may lock other airbag circuits.
B17281B›
DTC B17281B indicates the Supplemental Restraint System (SRS) detects the right knee airbag (front passenger knee airbag) igniter circuit resistance exceeds the normal threshold (typically >3.5Ω; normal range 1.5-3.0Ω). This open-circuit fault indicates high resistance or an open circuit in the airbag igniter circuit. When the SRS control module detects continuously high resistance, it flags the airbag as abnormal, illuminates the airbag warning light, and disables deployment of the affected airbag. During a collision, the right knee airbag may fail to deploy, disabling lower limb and pelvic protection for the front passenger and increasing the risk of injury.
B172B›
DTC B172B indicates the SRS (airbag) control unit detects an open circuit or disconnected condition in the left middle-row side airbag module (typically located inside the left B-pillar trim or on the side of the left rear seat). An abnormal resistance value in the circuit between the control unit and the airbag squib (typically infinite or outside the normal 2-3Ω range) causes the system to determine the airbag module is physically disconnected or internally open. This fault prevents the left middle-row side airbag from deploying during a side-impact collision. The SRS system may also enter a degraded protection mode, continuously illuminate the instrument panel airbag warning light, and restrict seat belt pretensioner function on some models.
B172B1B›
DTC B172B1B indicates the Supplemental Restraint System (SRS) detected a communication loss between the left middle-row (second-row left-side) side airbag module and the SRS control unit (ACU). This fault indicates an open airbag module circuit with resistance exceeding the threshold (typically >10Ω), preventing the control unit from detecting the module. Possible causes include a disconnected physical connector, broken wiring harness, faulty internal spiral cable (clock spring), or an open circuit within the module itself. Because the SRS uses a dual-stage deployment circuit, this fault prevents the left middle-row side airbag from deploying during a collision. It may also trigger a system self-check lockout, affecting the entire side airbag system.
B172C›
DTC B172C indicates the Airbag Control Unit (ACU) detects an abnormally low-resistance path (typically <1Ω) between the left second-row side airbag squib circuit and body ground. In the SRS system, normal airbag squib resistance is approximately 2.0-3.0Ω. When the ACU detects a short to ground in the circuit, it registers a severe fault and triggers protection mode: immediately disconnecting power to the airbag circuit, illuminating the SRS warning lamp, and disabling left second-row side airbag deployment. This fault prevents the side airbag from inflating normally to protect the occupant during a collision, or in extreme cases, risks unintended deployment due to intermittent wiring contact.
B172C11›
DTC B172C11 indicates the SRS (Supplemental Restraint System) detected an abnormally low-resistance path from the left second-row side airbag ignition circuit (usually the left B-pillar side airbag or seat side airbag) to body ground (GND), with a resistance typically <1Ω. The airbag system ignition circuit features a dual-circuit redundant design (high side and low side). Under normal conditions, resistance to ground should be >100kΩ. Upon detecting a short to ground, the SRS ECU identifies a risk of unintended deployment or failure to deploy. The ECU immediately illuminates the airbag fault warning lamp and disables that side airbag and any linked restraint systems (such as the seatbelt pretensioner). This is a hard short circuit, not an intermittent fault. Repair immediately for occupant safety.
B172D›
DTC B172D indicates the Supplemental Restraint System (SRS) detects a short to vehicle power (B+) in the Left Second Row Side Airbag Module ignition circuit. During self-diagnostics or continuous monitoring, the Airbag Control Unit (ACU) detects an abnormally high voltage (near 12V battery voltage) in the left second row side airbag deployment circuit. This exceeds the normal monitoring range (typically a low voltage or specific resistance value). This short to power forces the airbag system into fail-safe mode, disables the affected airbag to prevent accidental deployment, and illuminates the airbag fault warning lamp. As the second row side airbag is part of the passenger restraint system, this fault constitutes a severe safety risk. The short circuit can prevent the airbag from deploying during a collision or, in extreme cases, trigger unintended deployment.
B172D12›
In DTC B172D12, "B" indicates the Body/Safety system, "172D" identifies the Left Middle Row Side Airbag, and "12" indicates a Short to B+. This fault indicates the airbag control unit (SRS ECU) detects abnormal continuity between the Left Middle Row Side Airbag squib circuit and the vehicle power supply (12V). Under normal conditions, the airbag squib resistance is approximately 1.5-3.0Ω. The SRS ECU monitors circuit current and voltage through the low-side or high-side driver circuit. When the ECU detects circuit voltage continuously exceeding the threshold (typically >5V and approaching battery voltage), it identifies a short to B+. This fault prevents normal airbag deployment (causing failure to deploy or unintended deployment during a collision). As a hard fault, it triggers a continuous SRS warning light, forces the system into fail-safe mode, and disables the affected airbag function.
B1730›
DTC B1730 indicates the airbag control unit (SRS ECU) detects a resistance of 0 ohms in the left second-row side airbag firing circuit (typically located inside the left B-pillar trim or on the side of the left second-row seat). This indicates a short to ground in the firing circuit, damaged wiring harness insulation shorting to ground, or an internal short circuit in the airbag module inflator. This fault forces the SRS system into fail-safe mode, preventing the left second-row side airbag from deploying during a side impact, and continuously illuminates the instrument cluster airbag warning light. Unlike high resistance (open circuit), a 0-ohm resistance typically means current flows directly to ground without passing through the inflator. This is a hard short circuit fault and requires immediate repair.
B17301A›
DTC B17301A indicates the Supplemental Restraint System (SRS) detected a resistance of 0 ohms in the left middle-row (second-row left-side) side airbag module firing circuit, indicating a hard short circuit. Normal airbag squib resistance is between 2.0 Ω and 4.0 Ω. A resistance of 0 ohms indicates current passes directly through the circuit without load. Possible causes include an internal short circuit in the airbag ignition wire, a wiring harness short to ground, a short circuit between connector terminals, or a fault in the SRS control unit (ACU) internal detection circuit. Upon detecting this fault, the ACU immediately illuminates the airbag warning lamp and disables the left middle-row side airbag to prevent accidental deployment from the short circuit. Consequently, the airbag will fail to deploy during a collision, posing a severe safety hazard.
B1731›
DTC B1731 indicates the Supplemental Restraint System (SRS) control unit detects the igniter circuit resistance for the left second-row side airbag module (typically located inside the left B-pillar trim panel or on the side of the left rear seat) falls below the normal threshold (BYD models typically specify 1.5-2.5Ω; refer to the workshop manual for exact specifications). Low resistance indicates an abnormal low-resistance path in the circuit. Potential causes include an internal short circuit in the igniter, a wiring harness short to ground, a short between connector terminals, or a faulty internal sampling circuit in the SRS ECU. This fault forces the SRS into fail-safe mode. During a side impact, the airbag may fail to deploy, or in extreme cases, trigger inadvertently. The instrument panel airbag warning light remains illuminated, indicating limited occupant protection system functionality.
B1732›
DTC B1732 indicates the Airbag Control Unit (ACU) detects the Left Middle Row Side Airbag Module squib circuit resistance falls outside the manufacturer's normal threshold (BYD standard is typically 1.6-2.0Ω, with a ±0.3Ω tolerance). "Resistance too high" usually means the resistance exceeds the upper limit (e.g., >2.5Ω or approaching an open circuit), indicating a high-impedance connection in the circuit. Connector oxidation, poor wiring harness connections, an internal open circuit in the airbag module, or increased partial winding resistance can cause this condition. Essentially, the SRS self-check detects reduced reliability in the secondary protection circuit. This condition can prevent the airbag from deploying fully within the specified time (typically <10ms) or with sufficient energy during a side-impact collision, degrading or disabling side-impact protection for the left middle-row occupant.
B1735›
DTC B1735 indicates the airbag control unit (SRS ECU) detects a communication loss or abnormal circuit resistance in the second-row right side airbag module (typically located in the side of the second-row right seat or inside the C-pillar/door trim panel). Specifically, the inflator circuit of this airbag assembly is open (infinite resistance), or the communication line between the module and the SRS ECU is open. This is an active safety system fault. During a side collision, this airbag may fail to deploy, leaving the second-row right occupant without side impact protection. Disconnected physical connections, damaged wiring harnesses, an open inflator inside the airbag module, or poor terminal contact at the SRS ECU typically cause this fault. Use the dedicated diagnostic tool (VDS2000/VDS3000) and the wiring diagram to pinpoint the fault.
B17351B›
DTC B17351B indicates the SRS (Supplemental Restraint System) control unit detects a communication interruption or open electrical connection between the right second-row side airbag module (typically located on the right rear seat side or C-pillar) and the main control unit. Specifically, this open circuit fault indicates the airbag ignition circuit resistance falls outside the normal range (typically >10Ω or reading infinite). This fault prevents the affected side airbag from deploying normally during a collision. It may also deactivate the entire airbag system (entering fail-safe mode) and retain only the driver airbag function, severely compromising occupant side-impact protection.
B1736›
DTC B1736 indicates the Supplemental Restraint System (SRS) detects a short to body ground in the igniter circuit of the right second-row seat side airbag (Side Airbag Module, located on the side of the right second-row seat). Under BYD DTC coding rules, B1736 serves as the general identifier for this fault type. A specific short to ground typically corresponds to B173611 (hexadecimal 11 indicates a short to ground). This fault means the resistance between the two airbag igniter terminals, or between a terminal and the vehicle body, drops abnormally low (typically below 1.0 Ω). The SRS ECU determines this is a short circuit. This fault causes the airbag warning lamp to remain illuminated. The system automatically cuts off the affected airbag circuit to prevent accidental deployment. In a collision, the airbag may fail to deploy normally, severely compromising occupant safety. Applicable models primarily include the Tang, Song MAX, and other 6-seat or 7-seat vehicles equipped with second-row side airbags.
B173611›
DTC B173611 indicates the SRS (Supplemental Restraint System) control unit detects an abnormal short to body ground in the firing circuit of the right second-row side airbag module (typically located on the side of the right second-row seat or the lower B-pillar). The airbag module contains an electric squib (igniter) controlled by the airbag ECU, with a normal resistance between 1.5 and 2.5 Ω. The diagnostic system logs a short to ground when the circuit-to-ground resistance drops below the threshold (typically under 1 Ω or a specific calibrated value). This fault produces the following consequences: 1) The side airbag fails to deploy during a collision, resulting in a loss of side-impact protection; 2) In extreme cases, short-circuit current triggers unintended airbag deployment, causing occupant injury; 3) The SRS enters fail-safe mode, disabling the entire vehicle airbag system. This constitutes a highest-severity electrical safety fault requiring immediate repair.
B1737›
DTC B1737 indicates the Supplemental Restraint System (SRS) detected abnormal continuity between the right middle-row side airbag squib circuit (typically the second-row right seat side airbag or right curtain airbag) and the vehicle power supply (B+, battery positive). The SRS ECU monitors the airbag inflator resistance via an internal current source (normal resistance: 2.0–3.0 Ω). If the ECU detects the voltage across the inflator circuit remaining close to battery voltage (>5 V and approaching 12 V) instead of the expected low potential or floating state, it identifies a short to power. This fault prevents the airbag from deploying normally during a collision because the short circuit bypasses the firing current. In extreme cases, abnormal current can cause unintended deployment, posing a severe safety hazard.
B173712›
DTC B173712 indicates a short to power in the firing circuit of the right second-row side airbag module in the Supplemental Restraint System (SRS). Specifically, the "right second-row side airbag" typically refers to the side impact airbag located in the right B-pillar or the side of the right seat. The "12" suffix indicates a circuit short to battery positive (B+). This fault causes the following conditions: 1) The airbag may fail to ignite and deploy during a collision, resulting in a loss of side impact protection. 2) In extreme cases, unintended triggering may cause accidental airbag deployment. 3) The SRS control unit detects abnormally high circuit voltage (typically above 4.5V) and enters fault protection mode. This may disable the entire airbag system and continuously illuminate the instrument cluster airbag warning light.
B173A1A›
DTC B173A1A indicates the right middle-row side airbag (typically located on the side of the right second-row seat or inside the C-pillar trim panel) igniter circuit resistance measures 0 Ω. In the Supplemental Restraint System (SRS), normal airbag igniter resistance ranges between 2.0 and 5.0 Ω. A resistance of 0 Ω indicates a short to ground or a short between circuit wires, preventing the Airbag Control Unit (ACU) from establishing a normal monitoring circuit. This safety-critical fault prevents the airbag from deploying during a collision, continuously illuminates the instrument panel SRS warning lamp, and may force the entire airbag system into fail-safe mode.
B173B›
DTC B173B indicates an abnormal electric A/C compressor speed feedback signal or a communication fault between the compressor controller and the motor. In BYD new energy models (e.g., Tang, Song, Qin, and Yuan series), this DTC belongs to the HVAC subsystem within the Body Control system and specifically involves the electric compressor closed-loop control circuit. The ECU sets this DTC when the compressor controller (IPM) fails to receive a valid pulse signal from the Hall speed sensor for more than 3 continuous seconds, or when the deviation between the detected actual speed and the target commanded speed exceeds the calibrated threshold (typically >500 rpm). This fault forces the A/C system into fail-safe mode and stops compressor operation. Symptoms include a complete lack of cooling, intermittent cooling, or a sharp decrease in cooling performance. The instrument cluster A/C warning lamp may also illuminate. Prolonged operation with this fault can degrade high-voltage system insulation or cause controller overcurrent damage.
C102A00›
DTC C102A00 indicates the IPB (Integrated Power Brake) control unit detects an invalid or abnormal reverse gear signal. In BYD DM-i and e-Platform 3.0 models, the gearshift controller (or TCU) typically sends the reverse gear signal to the IPB system via the CAN bus. This signal activates reverse-related brake control strategies, such as reverse automatic hold release logic, reverse misapplication prevention (R-AEB), and hill reverse assist control. The IPB triggers this fault code if it fails to receive a valid reverse gear signal within a predetermined time, if the received signal contradicts actual vehicle state logic (e.g., vehicle speed conflicts with the reverse gear signal), or if the signal voltage or message format falls outside the valid range. This fault may prevent the automatic hold system from releasing normally during reverse maneuvers, cause abnormal brake pedal feel, or trigger the brake system degraded protection mode, compromising reversing safety.
B173C›
DTC B173C indicates the Supplemental Restraint System (SRS) detects the Right Second Row Side Airbag squib circuit resistance exceeds the calibrated threshold (typically >4.5Ω). This fault is an active diagnostic result of the SRS system, indicating a high-resistance condition in the circuit between the Airbag Control Unit (ACU) and the airbag module. Causes for excessive resistance include increased contact resistance, a partially broken wiring harness, terminal oxidation, or an aging squib wire inside the airbag module. This fault causes the system to mark the airbag circuit as 'unreliable', meaning the airbag may fail to deploy during a collision. The fault typically illuminates the instrument cluster airbag warning light (SRS light) continuously, and some models also sound a warning buzzer.
B1740-00›
This DTC indicates that during the self-check, the SRS (Supplemental Restraint System) control module detects, through its internal diagnostic circuit, an open circuit in the left rear side airbag (left curtain airbag or seat side airbag) communication line, or the airbag module initialization resistance falls outside the normal range (typically 2.0-3.0 ohms). Consequently, the SRS module cannot confirm the physical presence or electrical connection integrity of the airbag, and the system registers the airbag as "not present". In a collision, this airbag may fail to deploy, disabling side impact protection for the left rear passenger. Additionally, the SRS system enters fail-safe mode, which may alter the deployment logic of the entire airbag system and illuminate the instrument cluster airbag fault warning lamp.
B1740›
DTC B1740 indicates the Airbag Control Unit (ACU) detects an open circuit in the Left Rear Side Airbag during the self-check, or the system configuration marks the airbag module as 'not present'. Hardware causes typically include an open circuit between the ACU and the left rear side airbag (resistance exceeds the threshold, typically >6Ω) or an internal open circuit within the airbag module itself. Software configuration issues occur when the vehicle configuration code (VCU configuration) mismatches the actual hardware. Examples include configuring a low-spec vehicle with high-spec parameters or installing a seat assembly without a side airbag. This fault prevents the side airbag from deploying during a collision, severely compromising side-impact protection. The SRS system also illuminates the instrument cluster airbag warning lamp and may disable the entire airbag system to enter safety mode.
B1741-00›
DTC B1741-00 indicates the airbag system (SRS) control module detected a short to ground in the Left Rear Side Airbag deployment circuit. The SRS ECU continuously monitors the airbag inflator resistance via its internal diagnostic circuit (normal range: 2.0-3.0 ohms). When the system detects an abnormally low circuit resistance (near 0 ohms) or a short-to-ground path, it logs a short-to-ground fault. This fault prevents the affected airbag from deploying during a collision or, in extreme cases, risks unintended deployment due to wiring faults. Consequently, the SRS immediately illuminates the airbag warning lamp and disables the entire airbag system to protect occupants.
B1741›
DTC B1741 indicates the Airbag Control Module (ACM) detected a short to ground in the Left Rear Side Airbag squib circuit. In the SRS system, two wires (high side and low side) connect each airbag inflator to the ACM. These circuits normally maintain a high-impedance state. The ACM logs a short to ground when it detects an abnormally low circuit resistance (close to 0Ω) or a voltage drop to ground potential. This condition causes the following: 1) The airbag system enters fail-safe mode, disabling this airbag and related airbags. 2) The airbag warning light (SRS light) remains illuminated. 3) The airbag fails to deploy during a collision, severely compromising occupant safety. 4) The system may store related fault codes, such as B1740 (airbag not present). Different vehicle models or model years may define B1741 as a left front window lift switch signal fault in the Left Body Domain Controller (LBDC) system, reflecting the evolution of BYD fault codes across electrical architectures.
B174111›
DTC B174111 indicates a short to ground in the Left Rear Side Airbag ignition circuit. In the SRS (Supplemental Restraint System), this means the wiring between the Airbag Control Unit (ACU) and the left rear side airbag module (typically the low-side drive wire or high-side power wire) has an abnormal electrical connection to vehicle ground (GND). This drops the circuit resistance abnormally, typically below 1-2 ohms. This fault causes the ACU to detect a short-circuit risk in the airbag circuit. To prevent accidental deployment or insufficient ignition energy, the system disables the airbag and illuminates the instrument cluster airbag warning light. The left rear side airbag typically mounts inside the C-pillar trim panel or on the side of the rear seat. The wiring harness routes through crush-prone areas, such as the sill trim panel and seat rails, making mechanical damage a frequent cause of this fault.
B1742-00›
DTC B1742-00 indicates the SRS (airbag) control module detects an abnormally low-resistance short circuit between the Left Rear Side Airbag squib circuit and the vehicle positive power supply (+B, typically 12V battery voltage). Under normal conditions, high resistance isolates the airbag squib circuit from both power and ground. The SRS module internal capacitor releases current only at the moment of deployment. A short to power causes: 1) airbag deployment failure (the power supply bypasses the trigger current); 2) a risk of unintended deployment (if short circuit resistance changes or voltage fluctuates); 3) the SRS system to enter fail-safe mode, disabling all airbag functions. This fault is a continuous, non-intermittent hard short.
B1742›
DTC B1742 indicates an abnormal short circuit between the left rear side airbag ignition loop (typically installed in the left rear seat backrest or C-pillar) and the vehicle power supply positive (B+). In the Supplemental Restraint System (SRS), the airbag module connects to the Airbag Control Unit (ACU) via two wires. Normal wiring harness resistance measures approximately 2-3 ohms. The diagnostic system triggers this fault code upon detecting a short to power in this circuit (voltage approaching 12V battery voltage instead of the normal low-voltage signal). This fault is extremely dangerous. The short circuit can cause unexpected airbag deployment while driving, severely injuring occupants. Furthermore, the system enters protection mode and disables the airbag, preventing inflation during a collision and eliminating side-impact protection. Additionally, the SRS illuminates the instrument cluster airbag warning light and may lock the entire airbag system, disabling all airbags.
B174212›
DTC B174212 indicates the SRS (Supplemental Restraint System) electronic control unit detects an abnormally low-resistance connection between the left rear side airbag squib circuit (typically installed in the left rear C-pillar or left rear door frame side panel) and the vehicle power supply positive terminal (B+). Under normal conditions, the airbag squib circuit remains in a high-resistance open state. The SRS ECU momentarily closes the circuit only during a collision to release current and ignite the gas generator. A short to power causes: 1) The airbag to fail to deploy during a collision (the power supply bypasses the current, preventing sufficient heat generation to ignite the squib). 2) A potential risk of unintended airbag deployment in extreme cases due to the circuit fault (although modern SRS systems typically feature shorting bars and dual-stage trigger protection). Affected components include the left rear side airbag module, C-pillar/floor wiring harness, seat wiring harness (if the seat integrates the airbag), and the SRS ECU. As a Level 3 fault (the highest safety classification), the system immediately illuminates the instrument cluster airbag warning lamp and disables the entire airbag system.
B174400›
The BYD Qin PRO series defines DTC B174400 as "Crash Output Fault", a critical safety fault in the SRS airbag system. This indicates the airbag control unit (ACU) detects a circuit abnormality when attempting to output a crash trigger signal to other vehicle systems. In BYD new energy vehicles, this specifically refers to a crash signal interaction fault between the ACU, the high-voltage system manager (BMS/VCU), and the body control module (BCM), including: 1) A short to power/ground or an open circuit in the crash output signal line; 2) Damage to the ACU internal crash output driver MOSFET circuit; 3) Abnormal feedback signals from receiving actuators (e.g., high-voltage power cut-off relay, fuel pump cut-off relay, and door unlock relay). During a collision, this fault prevents high-voltage system disconnection (electric shock risk), fuel pump shutoff (fire risk), and automatic door unlocking (hindering escape and rescue). This significantly increases the risk of secondary accidents. Hyundai/Kia vehicles typically define this DTC as "Front Passenger Side Pressure-Type Side Impact Sensor ID Error", indicating cross-brand definition differences. For BYD systems, prioritize diagnosing the crash output signal circuit and ACU driver circuit faults.
B174A-00›
This fault code indicates the measured resistance of the left rear side airbag (Side Airbag, Left Rear) firing circuit is 0 ohms, confirming a short circuit. In the BYD SRS (Supplemental Restraint System), normal airbag squib resistance ranges from 1.5 to 3.5 ohms. A 0-ohm reading indicates a direct short circuit between the firing circuit power wire (Squib+) and ground wire (Squib-), or the airbag module detects abnormally low internal resistance. This condition causes the SRS control unit to identify an unintended deployment risk, illuminate the airbag warning light, and disable the left rear side airbag. Unlike a "resistance too high/open circuit" fault (infinite resistance), damaged wiring insulation, connector water ingress, or mechanical damage typically causes short circuits. Inspect the circuit immediately to prevent potential overheating.
B174A›
DTC B174A indicates the measured resistance of the Left Rear Side Airbag ignition circuit is 0 ohms, representing a short circuit fault in the airbag system. Normal airbag igniter resistance ranges from 1.5 to 3.5 ohms. A 0-ohm reading indicates a short to ground or short to power in the ignition wiring, allowing current to directly bypass the igniter. This causes the SRS control unit to identify the airbag circuit as faulty, illuminate the airbag warning light, and disable deployment of the Left Rear Side Airbag. In a side collision, this airbag may fail to inflate normally, severely compromising side impact protection for rear passengers. This fault represents a loss of airbag ignition circuit integrity. Repair the system immediately to ensure correct operation of the passive safety system.
B174B-00›
This DTC indicates the firing circuit resistance of the left rear side airbag (typically integrated into the left rear door C-pillar trim panel or the side of the left rear seat backrest) falls below the SRS control module threshold (normal range 2.0-3.0Ω; fault threshold typically <1.0Ω or near 0Ω). Low resistance indicates an abnormal low-resistance path in the circuit. Causes include a short to ground, damaged wiring harness insulation, shorted connector pins, or an internal short in the airbag inflator bridge wire. This fault forces the SRS system into a degraded mode and illuminates the airbag warning light. During a collision, the affected airbag may fail to deploy (as the control module detects a short and disables the firing circuit) or, in extreme cases, deploy unintentionally.
B174B›
This DTC indicates the SRS (Supplemental Restraint System) ECU detects that the igniter circuit resistance for the left rear side airbag (typically located in the left rear seat backrest side or C-pillar trim panel) is below the calibrated threshold (typically < 1.5Ω; standard value 2.0 ± 0.3Ω). Electrically, low resistance usually indicates a parallel resistance path in the circuit. Possible causes include an inter-turn short circuit in the internal igniter coil, damaged wiring harness insulation shorting to body ground, or conductive contamination between connector terminals. This fault forces the SRS into a degraded mode. During a collision, the ECU may disable deployment of the affected airbag due to the circuit anomaly (fail-safe). Furthermore, if the resistance drops near 0Ω, the system risks inadvertent deployment. This safety-critical fault requires immediate repair.
B174C-00›
DTC B174C-00 indicates the Airbag Control Unit (ACU) detects the left rear side airbag (typically located on the outboard side of the left rear seat backrest or inside the C-pillar trim panel) igniter resistance exceeds the calibrated threshold (normal range: 1.5-3.0 Ω, typically calibrated around 2.0 Ω). This SRS continuity monitoring fault indicates a high-resistance condition in the circuit between the ACU and the airbag igniter. Potential causes include an open circuit, poor contact, or an internal open circuit within the airbag assembly. This fault prevents the affected airbag from deploying during a collision. The system illuminates the airbag warning light and disables the associated airbag function.
B174C1B›
This fault code indicates the Airbag Control Module (ACM) detects the squib circuit resistance of the left rear side airbag (typically integrated into the left rear seat backrest side or C-pillar trim panel) exceeds the calibrated upper limit. Normal airbag squib resistance ranges from 1.5Ω to 3.0Ω. The ACM logs a 'high resistance' fault when it detects the value continuously exceeding the threshold (typically above 4.5Ω). This active safety system functional fault means the airbag may deploy abnormally, deploy late, or fail to deploy completely during a side-impact collision, disabling side protection for the left rear passenger. An abnormal drop in squib circuit conductivity causes this fault. Increased contact resistance, a partial open circuit, or an aging internal squib spiral coil can trigger this condition.
B174C›
DTC B174C indicates the SRS (Supplemental Restraint System) detects the inflator resistance of the left rear side airbag (usually located inside the left rear C-pillar trim panel or on the side of the left rear seat) exceeds the system-calibrated threshold (typically above 3.0Ω; normal range is 1.5Ω-3.0Ω). This fault indicates a high-resistance condition or open circuit in the airbag inflator circuit. Inflator aging, poor wiring harness contact, or a broken wire can cause this condition. This fault prevents the airbag from deploying correctly during a side-impact collision and continuously illuminates the dashboard airbag warning light (SRS light). The system enters fail-safe mode, and some models may limit the seat belt pretensioner function.
B1750-00›
This DTC indicates the SRS (Supplemental Restraint System) ECU cannot establish valid communication with the right rear side airbag module and detects an open circuit in the airbag circuit (resistance exceeds the normal 2-3Ω range, typically reading as infinite or >10Ω). This failure disables protection for the right rear occupant during a side impact and may trigger an SRS downgrade mode, affecting the coordinated deployment strategy of other airbags. On certain vehicle configurations, incorrect vehicle coding (flashing high-spec software to a low-spec vehicle) can cause a false DTC.
B1750›
DTC B1750 indicates the SRS (Supplemental Restraint System) control unit detects an open circuit, abnormal resistance, or a physically missing Right Rear Side Airbag module. This level 2 airbag system fault (a non-fatal hardware fault affecting passive safety functions) indicates the SRS control unit cannot establish normal communication with the right rear side airbag or detects infinite resistance in the airbag igniter circuit. This fault prevents the right rear side airbag from deploying during a collision, severely compromising side-impact protection. The instrument cluster continuously illuminates the airbag warning light. Possible causes include an open circuit in the airbag module wiring harness, a loose connector, an open circuit in the internal airbag igniter, or incorrect airbag assembly installation following vehicle modification or repair.
B1751-00›
B1751-00 is a Supplemental Restraint System (SRS) hard fault code indicating a short circuit to body ground (GND) in the right rear seat side airbag squib circuit (typically integrated into the seat backrest or C-pillar trim). The SRS ECU internal detection circuit continuously monitors the airbag squib circuit resistance (normal range: 2.0-3.0 Ω; 1.6-2.1 Ω on some models). The ECU registers a short to ground when it detects circuit resistance to ground below 1.0 Ω (near 0 Ω). This fault causes the following: 1) The affected airbag fails to deploy during a collision, losing its protective function. 2) The SRS enters fail-safe mode, which may restrict seat belt pretensioner operation. 3) The instrument panel airbag warning light remains illuminated, indicating a critical safety hazard. This is a level 3 severe fault requiring immediate repair.
B1751›
DTC B1751 indicates the SRS (Supplemental Restraint System) control module detects a short to ground in the right rear side airbag deployment circuit. Specifically, an abnormally low resistance path (typically less than 1 ohm) exists between the vehicle body ground and the igniter wiring for the right rear side curtain airbag (C-pillar side curtain airbag) or the right rear seat side airbag. The standard igniter resistance is 2.0 ± 0.3 ohms. When the ECU detects a circuit short to ground, it immediately sets this DTC and cuts off the airbag deployment circuit to prevent accidental deployment while driving or failure to deploy during a collision. This safety-critical fault causes the airbag warning light to remain illuminated and may fail to protect the right rear passenger during a crash.
B1752-00›
DTC B1752-00 indicates the right rear side airbag igniter circuit is shorted to vehicle power (B+). In the SRS (Supplemental Restraint System) circuit architecture, the airbag igniter is a low-impedance (nominal 2-5Ω) resistance wire. Normally, the SRS control unit uses an internal boost circuit to supply a momentary high current (approx. 1-3A) to deploy the airbag during a collision. Detecting a short to the 12V power supply in the igniter harness indicates an abnormal high-potential path in the circuit. This creates two risks: first, continuous power supply may cause accidental airbag deployment without a collision (although modern SRS controllers typically feature short-circuit protection); second, during an actual collision, the external power short prevents the control unit from forming an effective current loop to deploy the airbag, disabling the safety function. Consequently, the SRS control unit immediately illuminates the airbag warning lamp, stores this DTC, disables the right rear side airbag and related linked protection functions, and enters fail-safe mode.
B175111›
This DTC indicates the Supplemental Restraint System (SRS) detected an abnormally low-resistance connection (short to ground) between the right rear side airbag squib circuit (typically located on the outer side of the right rear seat or inside the C-pillar trim panel) and vehicle chassis ground (GND). Under normal conditions, the airbag squib circuit maintains a specific resistance (approximately 2-3Ω). When the ACU (Airbag Control Unit) detects circuit resistance near 0Ω, it registers a short to ground. This constitutes a critical safety fault. The system immediately illuminates the SRS warning lamp and disables the right rear side airbag and related coordinated protection functions to prevent accidental deployment while driving or deployment failure during a collision.
B1752›
DTC B1752 indicates a short circuit to battery positive (B+) in the RHS Rear Side Airbag squib circuit. In the Supplemental Restraint System (SRS), normal airbag inflator resistance is 2-3 ohms. The control unit determines circuit status by monitoring circuit current and voltage drop. When wiring harness insulation damage causes a short to the 12V power supply wire, the control unit detects an abnormally high potential (near battery voltage) and triggers DTC B1752. This fault causes the system to disable the affected airbag (fail-safe mode), preventing deployment during a collision. Additionally, continuous current creates a risk of unintended airbag deployment. The system classifies this as a level 3 severe fault.
B175212›
DTC B175212 indicates the Supplemental Restraint System (SRS) detects abnormal continuity between the ignition circuit of the right rear side airbag (Side Airbag Module, typically installed inside the C-pillar trim panel or on the side of the seat backrest) and the vehicle power supply positive (B+). In the SRS architecture, the airbag squib circuit must maintain high-resistance isolation from both power and ground. When the ECU detects that the circuit voltage continuously exceeds the threshold (typically over 80% of supply voltage) and the resistance falls below the specified value (<1kΩ), it identifies a short to power. This fault may cause: 1) Airbag deployment failure during a collision (ECU triggers protective cut-off). 2) Accidental airbag deployment in extreme cases due to false triggering. 3) SRS fail-safe mode activation, limiting overall vehicle airbag functions.
B175A-00›
DTC B175A-00 indicates the Airbag Control Module (ACM) detects 0 ohms resistance in the igniter (inflator) circuit of the right rear side airbag, typically located in the right rear seat side or C-pillar trim panel. Normal igniter resistance is 2.0-3.0 ohms. A resistance of 0 indicates a short circuit. Possible causes include an internal igniter short, a wiring harness short to ground, a short between connector terminals, or a control module internal driver circuit fault. This fault forces the SRS system into fail-safe mode. The right rear side airbag may fail to deploy during a collision, and the airbag warning lamp (SRS lamp) may illuminate continuously.
B175A›
DTC B175A indicates the Right Rear Side Airbag ignition circuit resistance measures 0Ω, indicating a short to ground in the airbag circuit or an internal short circuit in the airbag module. Normal airbag inflator resistance ranges between 1.5 and 3.5 ohms (typically 2.0-2.8Ω). When the SRS control module detects a resistance of 0Ω, it identifies a circuit short fault, immediately disables airbag deployment, and illuminates the instrument panel airbag fault warning lamp. Due to this fault, the Right Rear Side Airbag may fail to inflate and deploy during a side impact, severely compromising occupant protection. Common causes include wiring harness wear, connector water ingress, or an internal short circuit in the airbag module.
B175B-00›
DTC B175B-00 indicates the SRS (Supplemental Restraint System) control unit detects the right rear side airbag igniter circuit resistance (typically located in the right rear seat side or C-pillar trim panel) falls below the manufacturer threshold (normal range: 1.8–3.0 Ω; fault condition: below 1.0 Ω or near 0 Ω). This constitutes a low-resistance airbag circuit fault, meaning the control unit identifies a short circuit risk (wiring harness short to ground, wire-to-wire short, or internal short within the airbag module). Consequently, the affected side airbag may fail to deploy during a collision (as the ECU interrupts the trigger signal due to the circuit anomaly) or, in extreme cases, deploy unintentionally. Simultaneously, the SRS system illuminates the instrument cluster airbag warning light and may disable the entire airbag system to protect occupants.
B175B›
DTC B175B indicates the Airbag Control Unit (ACU) detects the igniter (squib) circuit resistance for the right rear side airbag (typically the right C-pillar curtain airbag or right rear seat side airbag) falls below the system threshold (generally <1.5 Ω). Normal airbag igniter resistance is 2.0-3.0 Ω. Low resistance indicates a circuit short to ground, a wire-to-wire short, or an internal short within the airbag module igniter. The ACU consequently registers the airbag as deployed or the circuit as faulty, disabling the airbag deployment function. During a side impact, the right rear side airbag fails to inflate and protect the occupant. This condition may trigger a continuous airbag warning lamp and constitutes a critical fault compromising passive safety.
B175B1A›
DTC B175B1A indicates the right rear side airbag igniter circuit resistance falls below the normal ECU threshold (typically below 1.0 Ω). In the BYD SRS (Supplemental Restraint System), standard airbag igniter resistance is generally 2.0–3.0 Ω. If the ECU continuously detects abnormally low circuit resistance, it logs a short circuit fault (indicating a possible short to ground or internal igniter short circuit). This fault causes the following: 1) The airbag may fail to deploy during a collision, resulting in a loss of side protection. 2) The airbag may deploy unexpectedly in extreme cases. 3) The SRS enters fail-safe mode and illuminates the airbag warning light. Common causes include wiring harness wear, connector water ingress, or an internal airbag module short circuit.
B175C-00›
DTC B175C-00 indicates the airbag control unit (SRS ECU) detects resistance in the Right Rear Side Airbag ignition circuit above the calibrated threshold. Normal airbag igniter resistance ranges from 1.6Ω to 2.4Ω (standard value approximately 2.0Ω). The ECU sets this fault when it detects resistance exceeding approximately 2.8Ω or a high-resistance state in the circuit. This fault indicates poor contact or a partial open in the ignition circuit, or abnormal internal resistance in the airbag module. As a functional fault in the passive safety system, it may prevent the side airbag from deploying during a collision. Because the SRS uses a two-stage diagnostic mechanism, this fault code continuously illuminates the airbag warning lamp and may force the entire airbag system into a downgraded protection mode, even if the vehicle remains drivable.
B175C›
DTC B175C indicates the airbag control unit (SRS ECU) detects that the igniter (squib) resistance for the right rear side airbag (typically located in the right rear seat backrest side or C-pillar area) exceeds the upper normal threshold. The SRS system continuously monitors each airbag igniter's resistance via a low-current circuit; the normal range is typically 1.5-3.0 ohms. If the resistance remains above approximately 3.5-4.5 ohms (specific thresholds vary by model), the system flags a 'resistance too high' condition. This fault indicates a high-resistance state in the airbag circuit. Possible causes include poor connector contact, a partially broken wiring harness, igniter degradation, or a faulty ECU internal sampling circuit. Safety Impact: Insufficient current may prevent this airbag from deploying during a collision, or the system may trigger a safety strategy disabling the entire airbag system, degrading occupant protection.
B175C1B›
DTC B175C1B indicates the SRS (Supplemental Restraint System) detects the right rear side airbag ignition circuit resistance exceeds the normal upper limit (typically > 10Ω; standard value 2.0-5.0Ω). This fault represents a high-resistance or open-circuit condition in the airbag ignition circuit. During a collision, the airbag control unit (ACU) may fail to supply sufficient current to ignite the gas generator. Consequently, the right rear side airbag will not deploy properly, severely compromising occupant side-impact protection. The manufacturer-specific '1B' sub-code typically indicates high resistance or an intermittent circuit.
B175D›
This fault code indicates the SRS (Supplemental Restraint System) control module detects a resistance of 0 Ω (or below 0.5 Ω) in the Left Front Side Curtain Airbag squib circuit. Under normal conditions, standard airbag squib resistance is 2.0 to 3.0 Ω (typical BYD specification is 1.5 to 4.0 Ω). A 0 Ω resistance indicates a short circuit in the squib circuit. Possible causes include a wiring harness short to ground, a wire-to-wire short (power wire shorted to ground wire), or an internal short in the squib bridge wire. This fault causes the SRS control module to identify the airbag circuit as abnormal, illuminate the airbag warning light, and disable Left Front Side Curtain Airbag deployment. In a collision, this side curtain airbag will fail to inflate and deploy, severely compromising side impact protection. Additionally, the short circuit creates a potential risk of unintended airbag deployment.
B175E›
DTC B175E indicates the Left Front Side Curtain Airbag ignition circuit resistance is below the normal threshold established by the SRS control unit (ACU) (typically 1.0–3.0 Ω, depending on model year). Low resistance indicates a short circuit, either complete (near 0 Ω) or partial. This fault causes the SRS system to flag the circuit as abnormal. During a collision, the airbag may fail to deploy or may deploy unintentionally. Consequently, the ACU illuminates the airbag warning light, stores the fault code, and may disable the entire airbag system to protect occupants.
B175D1A›
DTC B175D1A indicates the SRS (Supplemental Restraint System) ECU detects a resistance of 0 ohms or near 0 ohms in the left front side curtain airbag (head protection airbag) igniter circuit. Normal igniter resistance typically ranges between 2.0 and 3.0 ohms. A resistance of 0 ohms indicates a short circuit (short to ground or short between wires), not an open circuit. This short circuit prevents the SRS ECU from deploying the side airbag during a collision, or in extreme cases, abnormal current causes unintended airbag deployment. The ECU continuously monitors this hard fault and illuminates the airbag warning light. The system enters fail-safe mode, potentially limiting overall airbag system functionality.
B175F›
DTC B175F indicates the SRS (Supplemental Restraint System) control unit detects the left front curtain airbag (CAB) ignition circuit resistance falls outside the normal range (normal value: 2.0–3.0 Ω; fault threshold: >6 Ω or open circuit). This Level 2 airbag system fault means the affected curtain airbag may fail to deploy or deploy late during a collision, severely compromising occupant side-impact protection. The SRS ECU continuously monitors each airbag inflator circuit resistance using a Wheatstone bridge. Excessive resistance typically indicates poor circuit contact, high wiring impedance, or an open circuit within the inflator. On BYD new energy vehicles, check for potential electromagnetic interference from the high-voltage interlock circuit affecting the SRS.
B1760›
DTC B1760 indicates the SRS (Supplemental Restraint System) control unit detects the Left Front Side Curtain Airbag in a "not present" state. This means the ECU cannot identify the airbag electrical circuit during the self-check, or detects an open circuit or abnormal resistance (normal resistance is approximately 2-5Ω). The side curtain airbag (CAB) mounts inside the roof side rail and protects occupant heads during a side impact or rollover. This level 2 safety system fault prevents the left front side curtain airbag from deploying during a collision and continuously illuminates the instrument cluster airbag warning light. On certain BYD models (such as the Song MAX and Qin petrol version), this fault code may also indicate a driver seat position sensor circuit fault. The SRS uses seat position data to determine the airbag deployment strategy; a failed sensor can cause the system to log a similar code.
B17601B›
DTC B17601B indicates the airbag control unit (SRS ECU) detects a disconnected left front curtain airbag (located inside the driver-side roof rail), a communication interruption, or an abnormal resistance value. This is an airbag system hard fault, meaning the left curtain airbag may fail to deploy during a side impact, resulting in a loss of occupant head protection. The SRS ECU typically triggers this fault upon detecting infinite airbag inflator circuit resistance (open circuit) or resistance exceeding the normal threshold (standard value approximately 2.0-3.0 Ω) for longer than the specified time. Possible causes include physical wiring disconnections, module damage, or incorrect configuration. Inspect and repair immediately.
B1761›
DTC B1761 indicates the Left Front Side Curtain Airbag ignition drive circuit shorted to the vehicle power supply positive (B+). In the SRS system, normal airbag igniter resistance is approximately 2.0-3.0Ω. The control module determines circuit condition by monitoring voltage and resistance. If wiring harness insulation damage, misaligned connector terminals, or an internal airbag module fault causes the ignition circuit to contact a power wire, the control module detects an abnormally high voltage (near battery voltage). The module immediately sets DTC B1761 and enters fail-safe mode. This disables the Left Front Side Curtain Airbag and potentially related airbag functions, preventing deployment during a side impact and creating a severe safety hazard.
B176112›
DTC B176112 indicates a short to power in the left front wiper motor control circuit (although some documents incorrectly label this as an airbag fault, the BYD DTC system designates B17 for the wiper system). This occurs when the Body Control Module (BCM) detects an abnormally low-resistance connection between the left front wiper motor power or control line and battery positive (B+), causing an abnormal increase in circuit current. Symptoms include unintended wiper operation, inability to turn off the wipers, continuous high-speed operation, or complete failure. Severe cases risk wiring harness overheating, blown fuses, or electrical fire. Damaged wiring insulation, internal motor winding breakdown, or sticking relay contacts typically cause this short to power.
B1762›
DTC B1762 indicates the SRS (Supplemental Restraint System) detected a short to ground in the Left Front Side Curtain Airbag deployment circuit. Electrically, the side curtain airbag squib is a resistive load (typically 2-5 Ω). The SRS ECU controls it via a twisted pair. The ECU sets this code when it detects the circuit's insulation resistance to body ground falls below the threshold (typically <1 Ω) or when it detects abnormal ground voltage. This fault indicates: 1) Positive or negative squib wiring shorted to body metal within the A-pillar, B-pillar, or C-pillar trim, or in the headliner harness; 2) Igniter bridge wire insulation failure inside the airbag module; 3) Driver MOSFET breakdown inside the SRS ECU. This fault prevents the airbag from deploying during a collision (open-circuit protection mode) or, in extreme cases, creates a risk of unintended deployment. Consequently, the ECU illuminates the airbag warning light and disables the system.
C1101›
DTC C1101 indicates the ABS (Anti-lock Braking System) ECU detected its 12V low-voltage supply exceeds the system safety threshold (typically >16V-18V, depending on vehicle calibration). In BYD new energy vehicles, the DC-DC converter converts high-voltage traction battery power to supply 12V to the ABS. When the ECU detects an abnormally high supply voltage, it triggers the overvoltage protection mechanism. This may cause ABS, ESP, EBD, HHC (Hill Hold Control), and Automatic Emergency Braking functions to fail or enter a degraded mode. Unlike a high-voltage insulation fault, this indicates a power management abnormality in the 12V low-voltage system, which directly affects braking safety performance.
B176211›
DTC B176211 indicates the SRS (Supplemental Restraint System) ECU detected a short to ground in the left front side curtain airbag deployment circuit. Specifically, the SRS ECU continuously monitors the airbag inflator circuit voltage and resistance through its internal diagnostic circuit. When the ECU detects the circuit voltage remaining below the threshold (near 0V) or an abnormally low resistance (well below the normal 2.0-3.0Ω range), it identifies a short to ground. This fault prevents the side curtain airbag from deploying normally during a collision and may disable the entire SRS system (entering fail-safe mode), posing a severe safety hazard.
B1763›
DTC B1763 indicates the airbag control unit (SRS ECU) detects a 0 Ω (or near 0 Ω) resistance in the right front curtain shield airbag igniter circuit. Normal airbag igniter resistance is 2.0-5.0 Ω. A 0 Ω resistance indicates a short in the igniter circuit. Possible causes include an internal igniter short, a wiring harness short to ground (GND) or power (B+), or a faulty SRS ECU internal drive circuit. This fault causes the SRS system to enter fail-safe mode. During a collision, the affected curtain shield airbag may fail to deploy. The instrument panel SRS warning light illuminates continuously to indicate limited occupant protection system functionality.
B17631A›
DTC B17631A indicates the Right Front Side Curtain Airbag ignition circuit resistance is 0 ohms. This means the control module detects a short circuit (short to ground or short to power) in the airbag circuit. In the airbag system (SRS), normal inflator resistance ranges from 1.5Ω to 3.0Ω. A 0-ohm resistance indicates abnormal circuit continuity, presenting the following risks: 1) The side curtain airbag fails to deploy during a collision, resulting in a loss of side impact protection. 2) The wiring short circuit causes unintended airbag deployment in extreme cases. This constitutes a hard fault in the SRS and typically illuminates the SRS warning light continuously. The system enters fail-safe mode and disables the Right Front Side Curtain Airbag.
B1764›
DTC B1764 indicates the Right Front Side Curtain Airbag igniter circuit resistance falls below the SRS control unit (ACU) threshold (typically <1.0Ω or below 70% of the nominal 2.0Ω). This fault suggests an internal inter-turn short circuit in the airbag squib, or a short to ground or power in the wiring harness or connector, causing an abnormal drop in total circuit resistance. This critical safety fault causes the SRS system to detect a short-circuit risk in the airbag circuit, potentially triggering unintended deployment or failure during a collision. Consequently, the system illuminates the airbag warning light and disables the airbag's deployment function, severely compromising side-impact protection.
B1765›
DTC B1765 indicates the resistance in the right front side curtain airbag (RH Side Curtain Airbag) ignition circuit exceeds the normal threshold calibrated by the SRS ECU (typically 2.0-3.0Ω, with an upper limit of approximately 5-6Ω). This constitutes an airbag system loop integrity fault, indicating a high-resistance condition (approaching an open circuit) in the circuit between the SRS control unit and the right front side curtain airbag inflator. This fault causes the SRS ECU to determine the airbag cannot deploy normally, potentially failing to provide lateral head protection during a collision. The system illuminates the airbag warning light and may disable the entire airbag system. Although some OBD-II standards define B1765 as a seat circuit fault, the BYD SRS system (specifically in models like the Song MAX and Qin) defines this code as abnormal right curtain airbag resistance.
B17661B›
DTC B17661B indicates the airbag control unit (SRS ECU) failed to detect a valid electrical connection or the physical presence of the right front side curtain airbag during the system self-check. This "module missing/configuration error" fault signifies a complete communication loss between the ECU and the airbag module, rather than a simple igniter resistance anomaly. Root causes typically include missing airbag module power supply (12V constant or IG power), poor ground circuit, open or short circuits in the LIN/CAN communication lines, internal airbag module MCU fault, loose connections, backed-out pins, or oxidation at the wiring harness connector, or incorrect vehicle configuration data (e.g., failing to perform online coding after replacing the airbag module). This fault prevents the right front side curtain airbag from deploying during a collision, severely compromising occupant side impact protection. In certain repair scenarios and specific model years, this DTC also indicates a communication loss between the battery management system (BMS) and the vehicle control unit (VCU). Differentiate the diagnosis based on specific symptoms (airbag warning indicator illuminated vs. powertrain fault) and accompanying DTCs.
B1766›
DTC B1766 indicates the SRS (Supplemental Restraint System) control unit cannot identify or establish communication with the Right Front Curtain Shield Airbag. This fault constitutes an "airbag not present" condition; the ECU detects no load signal from the airbag module during the system self-check. This typically indicates an open airbag circuit (infinite resistance). Potential causes include a disconnected airbag connector, broken wiring harness, internal open circuit in the airbag module, or poor contact at the ECU terminal. This safety-critical fault prevents the right front curtain airbag from deploying during a collision, severely compromising side-impact protection.
B1767›
DTC B1767 indicates an abnormally low-resistance connection between the right front side curtain airbag inflator circuit and the vehicle positive power supply terminal (B+), resulting in a short to power. Under normal conditions, the airbag inflator circuit maintains high impedance (open-circuit state, with resistance typically between 2-5Ω) and conducts only momentarily when the Airbag Control Unit (ACU) triggers it. This fault indicates the airbag circuit may remain continuously energized even if the ACU does not issue a deployment command, causing two serious consequences: 1) The airbag may deploy unexpectedly during vehicle operation, causing serious occupant injury. 2) The system detects the abnormal voltage and enters protection mode, disabling the entire SRS system and preventing airbag deployment during a collision. This hard short-circuit fault typically causes the SRS warning lamp to illuminate continuously. Clearing the fault code will not resolve the issue.
B176712›
This DTC indicates the Airbag Control Unit (ACU) detects a short to positive (+B) in the RH front side curtain airbag ignition circuit. Under normal conditions, the airbag ignition circuit remains in a high-resistance state (infinite) or exhibits a specific resistance (typically >2Ω) only during circuit diagnostics. When the ACU detects continuous battery voltage (12V) or a resistance near 0Ω on this circuit, it logs a short to power. This hardwire short circuit causes the following: 1) Airbag fails to deploy during a collision (power supply clamps the circuit); 2) Unintended airbag deployment in extreme cases (if the ACU drive circuit and the shorted point form a complete circuit); 3) The ACU enters fail-safe mode, cuts power to this circuit, illuminates the SRS warning light, and degrades overall airbag system functionality.
B1768›
DTC B1768 on models such as the 2019 BYD Song MAX and 2020 Qin ICE indicates a short to ground in the right front side curtain airbag ignition circuit. The SRS ECU detects abnormally low resistance in the airbag inflator circuit (usually <2Ω), indicating damaged wiring insulation causing a short to body ground, or an internal short circuit in the airbag module. This fault prevents the affected airbag from deploying during a collision (fail-safe state) or, in very rare cases, creates a risk of unintended deployment due to circuit interference. This constitutes a highest-level safety fault. Note: Other BYD models (such as the Song Pro, Qin PLUS, and Han EV) may define B1768 as an abnormal left front door lock status signal. Verify the specific vehicle model and year.
B176811›
DTC B176811 indicates an abnormally low-resistance connection between the Right Front Side Curtain Airbag ignition drive circuit and vehicle ground (GND). In the BYD Supplemental Restraint System (SRS) architecture, the airbag igniter operates as a low-resistance inductive load (nominal resistance 2.0–3.0 Ω). The Airbag Control Unit (ACU) continuously monitors circuit current and voltage drop through the high-side/low-side drive circuits. When the ACU detects the insulation resistance between the ignition circuit and vehicle ground falls below the threshold (typically <200 Ω), the system registers a short to ground. This fault causes: 1) possible unintended airbag deployment from accidental grounding, risking occupant injury; 2) failure to deploy during a collision due to current bypass; 3) the SRS to enter fail-safe mode, disabling the affected circuit. Subtype identifier '11' indicates a continuous hard short (non-intermittent).
B176A-00›
This DTC indicates the airbag control unit (SRS ECU) detects a 0-ohm resistance in the left rear seatbelt pretensioner circuit, indicating a Short to Ground fault. As a pyrotechnic actuator, the pretensioner normally has a resistance of 2.0Ω-3.0Ω (depending on the vehicle model, typically 2.2Ω±0.3Ω). A 0-ohm resistance means current returns directly to ground without passing through the load. The SRS system identifies the pretensioner circuit as faulty. During a collision, the pretensioner may fail to activate and tighten the seatbelt, severely compromising occupant protection. This is a hard fault. Once confirmed, the system continuously illuminates the airbag warning light. Disconnecting the power usually fails to clear this fault.
B176A›
DTC B176A indicates the SRS (Supplemental Restraint System) detects a resistance of 0 ohms in the left rear seat belt pretensioner circuit. Normally, as a pyrotechnic device, the pretensioner resistance ranges from 1.5–3.0 Ω (depending on vehicle configuration). A resistance of 0 indicates a short in the circuit, typically a short to ground or an internal short within the pretensioner. This causes the Airbag Control Unit (ACU) to identify a pretensioner circuit fault. During a collision, the left rear seat belt pretensioner may fail to deploy, severely compromising rear occupant restraint protection. This fault also illuminates the instrument cluster SRS warning light and may lock the entire airbag system, preventing other airbags from deploying normally.
B176A1A›
DTC B176A1A indicates the Airbag Control Unit (ACU) detects a 0-ohm resistance in the left rear seat belt pretensioner. The SRS seat belt pretensioner contains a squib with a standard resistance of 1.5-2.5 ohms. A 0-ohm reading indicates a hard short circuit (short to ground, short to power, or internal short in the pretensioner squib). This fault causes the ACU to identify the pretensioner circuit as abnormal. During a collision, the pretensioner may fail to deploy and tighten the seat belt, or in extreme cases, deploy unintentionally. Because the SRS is a critical passive safety system, this fault illuminates the airbag warning lamp and may disable related airbag functions.
B176B-00›
This DTC indicates the SRS (Supplemental Restraint System) control unit detects the left rear seat belt pretensioner ignition circuit resistance is below the normal system-calibrated threshold (the standard value is typically 2.0Ω±0.3Ω; values below 1.0Ω trigger this code). The pretensioner uses a pyrotechnic igniter to tighten the seat belt during a collision, removing slack between the webbing and the occupant. Low resistance indicates a potential short circuit. Possible causes include a wiring harness short to ground, bridged connector pins, an internal short in the pretensioner igniter, or a faulty internal sampling circuit in the SRS control unit. This fault forces the airbag system into a degraded mode. The left rear pretensioner may fail to deploy during a collision or deploy unintentionally without a collision, severely compromising passive safety.
B176B›
This fault code indicates the airbag control unit (SRS ECU) detects the left rear seat belt pretensioner resistance is below the system threshold (typically below 2.0 Ω; standard value: 2.0–3.0 Ω). As a pyrotechnic safety device, the pretensioner contains a squib and a gas generator. Resistance must remain within a strict range to ensure reliable deployment. Low resistance indicates a short circuit risk, abnormally low resistance in the internal squib, or damaged wiring harness insulation reducing resistance between the positive and negative terminals. This causes two severe consequences: first, during a collision, the pretensioner may fail to ignite and deploy, eliminating safety restraint protection for the left rear passenger; second, the system may misidentify the condition as a short circuit and disable the trigger circuit. In extreme cases, the system activates fault protection mode, affecting the entire SRS operation. This fault illuminates the airbag warning light continuously and requires immediate repair.
B176B1A›
DTC B176B1A indicates the left rear seat belt pretensioner circuit resistance falls below the standard threshold set by the SRS control unit (ACU) (typically 1.5–3.0 Ω; the fault triggers below the lower limit). This is an SRS hard fault, indicating a potential or actual short circuit in the pretensioner igniter circuit. As a key passive safety system actuator, the pretensioner uses electrical current to trigger the igniter. This ignites the gas generator to tighten the seat belt during a collision (within approximately 15–20 ms). Low resistance may cause: 1) Unintended deployment (static electricity or electromagnetic interference causing accidental ignition); 2) The ACU to disable this trigger circuit in fail-safe mode, preventing seat belt pretensioning during a collision; 3) The ACU to lock out the entire SRS system if resistance drops near 0 Ω, disrupting the multi-airbag coordinated deployment strategy.
B176C-00›
This DTC indicates the airbag control unit (SRS ECU) detects the left rear seat belt pretensioner igniter resistance exceeds the calibrated threshold (normal range is typically 1.6-2.4Ω; the DTC triggers when detected resistance is >3.0Ω or an open circuit occurs). As a key actuator in the passive safety system, the pretensioner uses the igniter to detonate the gas generator during a collision, instantly tightening the seat belt to eliminate slack between the belt and the occupant. Excessive resistance indicates high impedance or a potential open circuit in the igniter circuit. This condition can prevent pretensioner deployment during a collision, severely compromising occupant restraint protection. This is a hard DTC. While the fault remains active, the system triggers a continuous warning and illuminates the airbag warning lamp. Some models may also limit power output or disable specific assistance functions.
B176C›
DTC B176C indicates the left rear seat belt pretensioner circuit resistance exceeds the normal threshold set by the SRS ECU (typically >3.5-4.0Ω; normal value is 2.0-3.0Ω). The pretensioner is a pyrotechnic safety device containing an igniter and a gas generator. Excessive resistance indicates a high resistance or open circuit condition within the circuit. Consequently, during a collision, the SRS ECU may fail to ignite the pretensioner charge. This failure prevents the seat belt from tightening, increases occupant forward displacement, and severely reduces crash protection. Additionally, the SRS system enters degraded mode, illuminates the airbag warning lamp continuously, and may disable the related side airbag function on certain models.
B176C1B›
DTC B176C1B indicates the airbag control module (SRS ECU) detects the left rear seat belt pretensioner circuit resistance exceeds the calibrated upper limit (typically >5.0Ω, normal range 2.0-3.5Ω). The pretensioner is a pyrotechnic safety device containing an internal resistance wire and propellant. The ECU determines its readiness by continuously monitoring the circuit current. Excessive resistance usually indicates a high-resistance connection in the circuit, a partial open circuit, or aging of the internal pretensioner coil. This condition can prevent the pretensioner from deploying correctly during a collision, seriously reducing the effectiveness of the occupant restraint system. This fault is a hard fault in the passive safety system. It generally illuminates the instrument cluster SRS warning light continuously and triggers a warning chime on some models.
B176D›
DTC B176D indicates the SRS (Supplemental Restraint System) ECU detects an open circuit in the left rear seat belt pretensioner circuit (infinite resistance), meaning the ECU cannot detect the pretensioner. This typically indicates a broken circuit connection between the pretensioner and the ECU, or an internal open circuit within the pretensioner. As a key passive safety actuator, the pretensioner rapidly tightens the seat belt via pyrotechnic deployment or motor operation during a collision, removing slack between the webbing and the occupant. This fault disables the left rear seat pretensioner during a collision, increasing occupant injury risk. The ECU continuously monitors the pretensioner circuit resistance (normal range: approx. 2.0-3.0Ω). It sets a 'not present' fault when it detects a resistance >10Ω or a complete open circuit.
B176D-00›
DTC B176D-00 indicates the airbag control unit (SRS ECU) detects an open circuit or missing load in the left rear seatbelt pretensioner circuit during the system self-check. The SRS ECU verifies pretensioner presence by monitoring the resistance across the pretensioner squib (normal value: 1.5-3.0 Ω). The ECU determines the pretensioner is "not present" if this resistance falls outside the threshold (open circuit >10 Ω or short circuit <0.5 Ω) or if it fails to receive the pretensioner LIN bus response signal. This safety-critical fault prevents the left rear seatbelt pretensioner from deploying and tightening during a collision, causing a loss of restraint protection for the rear passenger. It also continuously illuminates the instrument cluster airbag warning light. Some models may enter fail-safe mode, limiting vehicle power output.
B176D1B›
DTC B176D1B indicates the front passenger Occupant Classification System (OCS) detects an abnormal signal or missing sensor. The system uses pressure/capacitive sensors integrated into the front passenger seat cushion to detect seat occupancy and weight category. It transmits signals to the SRS airbag control unit to determine front passenger airbag deployment and deployment force during a collision. This fault indicates the airbag control unit cannot receive a valid occupancy status signal (typically indicating an open circuit, out-of-range resistance, or signal plausibility error). The system enters a fail-safe mode and defaults the front passenger seat status to "unoccupied". This may prevent the front passenger airbag from deploying during a collision, severely compromising passive safety performance.
B176E-00›
DTC B176E-00 is an SRS (Supplemental Restraint System) fault code indicating a short to body ground (GND) in the left rear seat belt pretensioner drive circuit. The pretensioner is a pyrotechnic actuator containing an igniter and gas generant. During a collision, the SRS ECU triggers the pretensioner. The resulting explosive force rapidly tightens the seat belt, removing slack between the occupant and the belt. This fault code indicates a short to ground (resistance below the threshold, typically <2Ω) in the wiring harness between the SRS ECU and the left rear pretensioner, or within the pretensioner itself. This causes the ECU to detect an abnormal current path. Upon detecting this fault, the SRS system illuminates the airbag warning lamp and enters fail-safe mode. This disables the left rear pretensioner and any linked side airbag functions, severely compromising crash safety performance.
B176E›
DTC B176E indicates the SRS (Supplemental Restraint System) control unit detects an abnormally low-resistance path between the Left Rear Seat Belt Pretensioner drive circuit and the vehicle power supply (+B), indicating a short to power. The pretensioner contains a squib controlled by the SRS ECU, with a normal operating resistance of approximately 2.0-3.0 Ω. If the wiring harness or connector shorts to a 12V power wire, the ECU detects an abnormally high voltage or resistance value, immediately sets this DTC, and enters fail-safe mode. This fault presents two risks: first, during a collision, circuit protection may prevent the left rear pretensioner from deploying, causing occupant restraint failure; second, the short-circuit current may accidentally trigger the squib, causing the seat belt to retract suddenly and injure the occupant. Consequently, the SRS system immediately cuts power to this circuit and illuminates the airbag warning lamp, potentially disabling the entire airbag system.
B176E12›
DTC B176E12 indicates abnormal continuity between the left rear seat belt pretensioner circuit and the vehicle power supply (B+), representing a "short to power". In the Supplemental Restraint System (SRS), the seat belt pretensioner is a pyrotechnic actuator. Under normal conditions, its circuit must remain isolated from the power supply; the SRS ECU supplies a momentary high-current ignition signal only during a collision. A short to power indicates: 1) continuous battery voltage across the pretensioner terminals risks accidental deployment (extremely dangerous); 2) the SRS ECU detects circuit voltage above the threshold (typically >5V or near 12V) and registers a severe fault; 3) the system immediately illuminates the airbag warning light and disables the entire airbag system (including front and side airbags), leaving the vehicle without collision protection. This fault involves the left rear seat belt pretensioner (typically located at the lower B-pillar or on the seat frame). The circuit comprises the ignition loop routing from the SRS ECU through the floor harness to the left rear seat.
B176F-00›
DTC B176F-00 indicates the SRS (Supplemental Restraint System) ECU detects an abnormal electrical connection between the left rear seat belt pretensioner drive circuit and the vehicle power supply (B+). The pretensioner consists of an igniter and a gas generator, with a normal resistance of 2.0-3.0Ω. Damaged wiring harness insulation, misaligned connector pins, or an internal pretensioner short circuit cause the ECU to detect an abnormally high circuit voltage (approaching 12V battery voltage) and trigger this DTC. This fault may result in: 1) Failure of the left rear pretensioner to deploy during a collision, compromising occupant protection. 2) Unintended pretensioner deployment in extreme cases, causing occupant injury. 3) The SRS entering fail-safe mode, disabling all vehicle airbags.
B176F›
This fault code indicates an abnormally low-resistance connection to body ground (GND) in the left rear seat belt pretensioner drive circuit. As a key actuator in the SRS (Supplemental Restraint System), the pretensioner typically uses a pyrotechnic or motor-driven design. During a collision, it rapidly retracts the seat belt webbing by igniting a gas generator or driving a motor, eliminating slack between the occupant and the seat belt. A short to ground means the positive circuit between the SRS ECU and the pretensioner (typically high-level triggered) shorts to the vehicle chassis ground, with resistance falling below the calibrated threshold (generally <2Ω). Upon detecting this fault, the SRS ECU immediately enters fail-safe mode, cuts power to the circuit to prevent accidental deployment or wiring overheating, and illuminates the airbag warning lamp. Consequently, the left rear seat loses pretensioner protection during a collision, and the occupant risks secondary impact injuries due to seat belt slack. The short-circuit current may also overheat and damage the SRS ECU driver chip, compromising the normal operation of the entire airbag system.
B176F11›
DTC B176F11 indicates the airbag control unit (SRS ECU) detects an abnormally low-resistance connection between the left rear seat belt pretensioner (squib) circuit and body ground (typically <2Ω). The pretensioner is a pyrotechnic actuator with a normal resistance of approximately 2.0-3.0Ω. A short to ground causes the SRS system to identify a safety risk in this circuit and trigger fail-safe mode. This mode immediately cuts power to the pretensioner circuit, illuminates the airbag warning lamp, and disables left rear pretensioner deployment during a collision. It may also affect the normal deployment logic of the entire airbag system. This is a hard DTC. The SRS ECU continuously logs the code while the short circuit exists. Repair the fault immediately to maintain passive safety system integrity.
B1770-00›
DTC B1770-00 indicates the SRS (airbag) control module detects the right rear seat belt pretensioner circuit resistance is 0 Ω or close to 0 Ω. Normally, the seat belt pretensioner acts as a pyrotechnic actuator with a standard squib resistance between 2.0-5.0 ohms. A resistance of 0 indicates a hard short in the circuit. Possible causes include an internal short in the pretensioner squib, a wiring harness short to body ground or power, or an internal short in the connector. This fault causes the SRS system to determine the pretensioner has failed. During a collision, the right rear seat belt pretensioner will not deploy, severely compromising the occupant restraint system's effectiveness. The fault also illuminates the instrument cluster airbag warning lamp and may inhibit the entire airbag system.
B1770›
This DTC indicates the SRS control module detects an abnormal 0 Ω resistance in the right rear seat belt pretensioner circuit. As a pyrotechnic device, normal pretensioner resistance ranges from 1.5 to 3.0 Ω. A 0 Ω reading typically indicates a short circuit. Possible causes include damaged wiring harness insulation shorting the positive and negative terminals, an internal connector short, a shorted internal resistance wire within the pretensioner body, or an SRS ECU internal drive circuit fault. This fault prevents the pretensioner from deploying during a collision. The SRS system may also disable airbag functions in the affected area, posing a severe safety hazard.
B17701A›
This DTC indicates the Airbag Control Unit (ACU) detects a 0-ohm resistance in the right rear seatbelt pretensioner circuit. As a key actuator in the passive safety system, the pretensioner contains an internal squib with a normal resistance of 1.5-3.0 Ω for circuit integrity monitoring. A resistance of 0 indicates a hard short in the circuit. Possible causes include a burned internal coil causing an inter-turn short, a wiring harness short to ground (vehicle body), or shorted connector pins. This fault prevents the ACU from sending a firing command to the pretensioner during a collision or triggers a system protection strategy that disables the entire right-side airbag circuit, severely compromising restraint protection for the right rear passenger during an accident.
B1771-00›
This fault code indicates the right rear seatbelt pretensioner circuit resistance falls below the normal threshold set by the SRS control unit (typically below 1.5Ω; standard value is approximately 2.0-3.0Ω). As a pyrotechnic safety device, the pretensioner contains an igniter and a gas generator. A low resistance value indicates an abnormally low-resistance path in the circuit. Potential causes include an internal pretensioner short circuit, a wiring harness short to ground, or connector pins shorted to ground. This fault forces the SRS system into a degraded mode. Consequently, the right rear pretensioner may fail to deploy during a collision, and the fault lamp remains illuminated to indicate system failure, severely compromising passive safety protection.
B1771›
DTC B1771 indicates the SRS (Supplemental Restraint System) control module detects the right rear seat belt pretensioner resistance is below the system-calibrated lower threshold (typically <1.0Ω or near a short-circuit value). The pretensioner is a pyrotechnic actuator containing an electric squib with a normal resistance of approximately 2.0±0.3Ω. Low resistance indicates a pretensioner internal short circuit, a wiring harness short to ground, connector water ingress causing electrochemical corrosion, or an SRS module internal sampling circuit fault. This fault triggers the airbag system fail-safe strategy. The affected seat pretensioner may fail to deploy in a collision, the AIRBAG warning lamp remains illuminated, and some models trigger a system buzzer alarm.
B1771A›
DTC B1771A indicates the SRS (Supplemental Restraint System) ECU detects the RH rear seatbelt pretensioner circuit resistance is below the calibrated threshold. (The standard value is typically 2.0 ± 0.5 Ω; a measured value below 1.2 Ω or near 0 Ω triggers this code). As a key passive safety system actuator, the pretensioner contains a pyrotechnic combustion chamber and a resistance wire. Low resistance indicates a short circuit risk (harness chafing to ground, water ingress at the connector, or an internal short from a melted resistance wire). To prevent accidental deployment or upon determining actuator failure, the SRS ECU illuminates the airbag warning light and may disable the RH rear side airbag and pretensioner deployment. This disables active tensioning protection for that seat during a collision, increasing occupant injury risk.
B1772-00›
DTC B1772-00 indicates the airbag control unit (SRS ECU) detects the right rear seatbelt pretensioner circuit resistance exceeds the calibrated range (normal range: 1.8–3.0Ω; high resistance typically indicates >5Ω or infinite). As a key passive safety system actuator, the pretensioner features a pyrotechnic design, using propellant gas to instantly tighten the seatbelt during a collision. High resistance indicates a high-impedance connection or open circuit. Causes include poor connector contact, a damaged wiring harness, or an open gas generator coil inside the pretensioner. This fault continuously illuminates the SRS warning light and can trigger a degraded system mode. During a collision, the pretensioner may fail to deploy, and the SRS ECU may suspend the right rear side airbag deployment logic, significantly reducing crash protection for the right rear passenger.
B1772›
DTC B1772 indicates the right rear seatbelt pretensioner ignition circuit resistance exceeds the standard upper limit (typically >3.6Ω or open circuit). The seatbelt pretensioner is a key SRS (Supplemental Restraint System) actuator containing an internal squib. During a collision, the SRS control unit (ACU) sends current to the squib to ignite the propellant, instantly tightening the seatbelt to protect the occupant. Excessive resistance indicates high resistance, poor contact, or a complete open circuit in the ignition circuit, preventing the ACU from activating the pretensioner. During a collision, the rear occupant on that side loses pretensioner protection, significantly increasing safety risks. Typical causes include connector oxidation, wiring harness damage, or internal pretensioner squib failure.
B17721B›
DTC B17721B indicates the airbag system (SRS) detects the right rear seat belt pretensioner circuit resistance exceeds the normal upper threshold. This pretensioner is a pyrotechnic actuator with a typical resistance range of 2.0–3.0 ohms. When the ECU detects resistance >4.0 ohms (or per the calibrated threshold), it determines a High Resistance fault. This fault prevents the seat pretensioner from deploying and retracting normally during a collision. Additionally, the SRS may enter a degraded mode, illuminating the instrument cluster airbag warning light continuously. On some models, other seat airbag functions may also be restricted. The DTC suffix "1B" typically indicates the specific circuit location or fault subtype, pointing to the right rear seat (Third Row/Second Row Right) pretensioner circuit.
B1773-00›
DTC B1773-00 indicates the airbag control unit (SRS ECU) failed to detect the electrical signal or communication response from the right rear seat belt pretensioner during the system self-check. This passive safety system hardwire/communication fault indicates an abnormality in the squib circuit between the SRS module and the right rear seat belt pretensioner. Causes include an open circuit, a short to ground or power, or the pretensioner internal igniter resistance falling outside the standard range (typically 1.5-3.5Ω). This fault prevents the pretensioner from deploying and tightening the seat belt during a collision, significantly reducing occupant protection. The SRS system also enters fail-safe mode, which may disable other airbags and illuminate the airbag warning light continuously.
P25C700›
This DTC indicates the brake booster (BLM/Booster) temperature sensor signal circuit voltage in the IPB (Intelligent Integrated Braking System) exceeds the normal range (0.5-4.5V). The ECU detects a voltage signal continuously exceeding the threshold (typically >4.8V). This condition usually indicates the temperature sensor signal wire shorts to the 12V power supply line (B+), or the internal thermistor fails due to a short circuit. Due to temperature monitoring failure, the IPB enters a safety degraded mode and limits the brake assist function. This limitation may cause a hard brake pedal and extended braking distance, constituting a severe fault that affects driving safety.
B1773›
On BYD new energy vehicles, DTC B1773 indicates a Cell Supervision Circuit (CSC) fault. This represents a Battery Management System (BMS) subsystem communication or sampling abnormality, rather than the seat belt pretensioner issue in the original description (the latter belongs to the SRS system, indicating a possible mix-up in fault code definitions). The CSC module continuously monitors key parameters within the power battery module, including individual cell voltage and temperature, and communicates with the main BMS via the internal CAN bus. The BMS sets DTC B1773 when it fails to detect a response signal from a CSC within the specified timeframe (communication timeout), receives out-of-range data (e.g., a -40°C open-circuit temperature reading), or detects a CSC address conflict or duplication. This fault activates the system safety protection strategy, limiting vehicle power output, disabling pure EV driving, or interrupting the charge/discharge process. It severely compromises power battery thermal management and safety monitoring functions and requires immediate repair.
B17731B›
This DTC indicates the SRS (Supplemental Restraint System) control module detects a missing signal or communication interruption from the right rear seat belt pretensioner during self-check or real-time monitoring. Specifically, the control module cannot identify the pretensioner’s electronic identification (resistance signature code or LIN/CAN node ID) or detects an open circuit, short to ground, or short to power. This prevents the seat belt at this position from tightening automatically during a frontal collision, increasing passenger forward displacement and significantly reducing restraint system effectiveness. The SRS system also illuminates the airbag fault warning lamp and may disable the related collision trigger logic. This is a critical fault affecting passive safety.
B1774-00›
This DTC indicates a short to vehicle power positive (B+) in the right rear seat belt pretensioner ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, the seat belt pretensioner is a pyrotechnic actuator. Its normal operating resistance is 2.0-3.0 Ω, and the circuit must remain isolated from the vehicle power supply. When the SRS ECU detects an abnormal resistance drop (near 0 Ω) or a short to power in this circuit, it triggers DTC B1774-00 and enters fail-safe mode. This fault prevents the right rear seat belt pretensioner from tensioning normally during a collision. In extreme cases, short-circuit current may cause the pretensioner to deploy unintentionally, presenting a severe safety hazard. The system illuminates the airbag warning lamp and may disable the entire right-side airbag system.
B177412›
DTC B177412 indicates the Supplemental Restraint System (SRS) detects an abnormally low-resistance connection between the right rear seat belt pretensioner drive circuit and the vehicle positive power supply (B+), indicating a short to power. The normal pretensioner igniter resistance is approximately 2.0-3.0Ω. The SRS ECU monitors circuit current and voltage to determine component status. If damaged wiring harness insulation causes the power wire (typically red/yellow) to contact the pretensioner drive wire, the ECU detects an abnormally high voltage (approaching the 12V battery voltage) and triggers this DTC. This fault causes the SRS to disable the right rear seat belt pretensioner circuit. During a collision, the pretensioner may fail to deploy and tighten the seat belt, creating a severe safety hazard. Additionally, the short to power creates a risk of unintended pretensioner deployment under extreme conditions. The system therefore classifies this as a severe fault (Level 3) and prohibits continued vehicle operation. Note: Repair practices for certain vehicle models may define this DTC as a seat ventilation system control circuit fault. Verify the definition against the specific vehicle configuration.
B1775-00›
This DTC indicates an abnormally low-resistance connection (typically <1 kΩ) between the right rear seat belt pretensioner squib circuit and vehicle chassis ground (GND). As a pyrotechnic safety device, the pretensioner relies on the SRS ECU to supply a high-current pulse during a collision. A short to ground causes: 1) abnormal circuit resistance, leading the ECU to register a device fault; 2) potential inadvertent deployment if the short-circuit current reaches the ignition threshold; 3) the SRS system to enter fail-safe mode, disabling the right rear pretensioner and associated seat belt reminder function. This is a hard fault in the passive safety system that directly affects the integrity of the occupant restraint system.
B1775›
DTC B1775 indicates the SRS (Supplemental Restraint System) detects a short to ground in the right rear seat belt pretensioner circuit. The seat belt pretensioner is a pyrotechnic actuator containing an explosive device and a resistance wire. Normal resistance is approximately 2-3 Ω. When the SRS control module detects circuit resistance below the threshold (typically <1 Ω) or an abnormal voltage drop to ground, it identifies a short to ground. This safety-critical fault causes: 1) the SRS to enter degraded mode, disabling right rear side impact protection; 2) continuous illumination of the airbag warning light; 3) a risk of unintended pretensioner deployment in extreme cases. The pretensioner wiring harness routes through the right rear door sill trim and C-pillar, exposing it to seat movement, liquid ingress, or mechanical damage.
B177511›
DTC B177511 indicates a short to ground in the right rear (RR) seat belt pretensioner ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, the airbag control unit (ACU) sets this DTC when it detects the right rear seat belt pretensioner drive circuit resistance falls below the threshold (typically <1.0Ω, normal range 2.0-3.0Ω) or detects an abnormal drop in the circuit insulation resistance to body ground. A short to ground prevents normal pretensioner deployment (failing to ignite the gas generator to tighten the seat belt during a collision). Simultaneously, the ACU illuminates the airbag fault warning lamp and may disable the entire side or rear SRS protection strategy, severely compromising occupant passive safety. This is a hard fault; once confirmed, it remains active and does not self-recover.
B1777›
This fault code indicates the Airbag Control Module (ACM) detects a 0 ohm circuit resistance in the left middle-row (second-row left) seatbelt pretensioner. In a normal SRS system, the pretensioner functions as a pyrotechnic actuator with a standard resistance typically between 1.8Ω and 3.0Ω (depending on the specific vehicle model). A 0 ohm resistance indicates a hard short in the circuit, usually a short to ground or a short between terminals. This causes the ACM to flag the pretensioner as failed. This condition triggers the airbag system fail-safe mechanism, potentially preventing the corresponding airbag and related restraint systems from deploying during a collision. The instrument cluster SRS warning light remains illuminated, posing a severe safety hazard.
B17771A›
DTC B17771A indicates the airbag control unit (SRS ECU) detects a circuit resistance of 0Ω or close to 0Ω for the second-row left seat belt pretensioner. Normally, the squib resistance inside an undeployed pretensioner is 2.0Ω±0.2Ω. A resistance of 0Ω indicates a hard short in the circuit. Potential causes include an internal short in the pretensioner coil, a wiring harness short to body ground, or a short between connector terminals. This is a safety system hard fault. The SRS ECU illuminates the airbag malfunction indicator lamp (MIL) and disables the second-row left seat belt pretensioner and potentially associated airbag functions. During a collision, the pretensioner fails to generate the designed pulling force to tighten the seat belt, reducing occupant restraint protection.
B1778›
DTC B1778 indicates the left middle-row (second-row left) seat belt pretensioner resistance falls below the normal threshold set by the SRS ECU. Standard resistance is typically 2.0–5.0 Ω; the ECU sets the fault upon detecting <1.5 Ω or near 0 Ω. The pretensioner is a pyrotechnic safety device containing an internal heating wire and pyrotechnic charge. During a collision, the ECU triggers deployment to rapidly tighten the seat belt. Low resistance typically indicates a circuit short to ground, an internal short in the pretensioner heating wire, or a grounded connector terminal. Consequently, the SRS system flags a risk of unintended deployment or functional failure, illuminates the airbag warning light, and may disable related crash protection functions. On BYD e-Platform and DM models, this fault may also affect the vehicle high-voltage interlock logic (some models link seat belt status to high-voltage readiness).
B1779›
DTC B1779 indicates the SRS (Supplemental Restraint System) control module detected the second-row left seat belt pretensioner circuit resistance exceeds the calibrated threshold (typically >3.5-4.0Ω; normal range is 1.6-3.0Ω). This passive safety system circuit integrity fault indicates a high-resistance state in the pretensioner deployment circuit. Potential causes include poor connections, an open circuit in the wiring harness, or an aging gas generator coil inside the pretensioner. During a collision, the SRS module might not supply sufficient current to deploy the pretensioner, preventing the seat belt from tightening promptly and increasing the risk of occupant injury. The system also illuminates the airbag warning lamp and may disable the associated airbag protection functions for that seat.
B1789-00›
This DTC indicates a short-to-ground fault in the Stage 2 firing circuit of the dual-stage driver airbag. In modern airbag systems, the second stage usually deploys simultaneously with or after the first stage during a severe collision, providing greater inflation volume for enhanced protection. A short to ground indicates damaged wire insulation or an internal connector fault in the circuit between the Airbag Control Unit (ACU) and the airbag squib. This creates a low-resistance path (typically <1Ω) between the circuit and the vehicle body ground. When the ACU detects an abnormal drop in circuit resistance, it immediately disables the Stage 2 airbag circuit and illuminates the airbag warning lamp to prevent accidental deployment or insufficient trigger energy. If a severe collision occurs in this state, the driver receives only first-stage airbag protection. The second-stage enhanced deployment function fails, but the first-stage airbag typically continues to operate normally.
B177A›
DTC B177A indicates the SRS (Supplemental Restraint System) control unit fails to detect the left middle-row (typically left second-row) seat belt pretensioner during self-diagnosis. This is an open-circuit fault; the ECU detects infinite pretensioner circuit resistance or resistance outside the normal threshold (standard value: 1.5-2.5Ω). The pretensioner is a key actuator in the passive safety system. During a frontal collision, a pyrotechnic igniter instantly tightens the seat belt to eliminate slack between the occupant and the belt. This fault indicates an open pretensioner circuit, preventing pretensioner deployment for this seat during a collision. This condition may also disrupt the coordinated deployment logic of the same-side or related airbags. "Not present" in this fault code does not indicate a missing physical component; it designates an electrical "communication loss" or "open circuit".
B177A1B›
DTC B177A1B indicates the SRS (Supplemental Restraint System/airbag system) control module detects an open circuit or resistance exceeding the normal threshold (typically >6Ω or infinite) in the left middle-row seat belt pretensioner circuit. The '1B' sub-code in the BYD diagnostic system typically indicates excessive circuit resistance or an open circuit, causing the ECU to determine the pretensioner is 'not present' or has lost communication. This fault prevents the system from triggering the left middle-row seat belt pretensioner pyrotechnic device during a collision, increasing occupant forward travel and reducing crash protection. The system illuminates the instrument cluster airbag fault warning light (SRS light) and may disable the deployment logic for the corresponding side airbag or curtain airbag.
B177B›
DTC B177B indicates the control circuit for the second-row left seatbelt pretensioner has shorted to the vehicle power supply positive (B+). In the BYD SRS system, the pretensioner operates as a pyrotechnic actuator. Under normal conditions, the SRS ECU controls the pretensioner via a low-side drive and, during a collision, supplies an instant high current (approximately 2-3A) to ignite the gas generator. A short to power means the circuit continuously carries an abnormally high potential (12V). This may result in the following: 1) The SRS ECU falsely detects a permanent trigger state or wiring fault, activating the system protection mechanism. 2) The SRS ECU disables the entire airbag system, preventing protection during a collision. 3) The pretensioner accidentally deploys or the ECU internal driver circuit burns out in extreme cases. This is a hard fault and requires immediate repair.
B177B12›
DTC B177B12 indicates a short circuit to vehicle power (+12V B+) in the firing circuit of the left second-row seat belt pretensioner within the Supplemental Restraint System (SRS). The Airbag Control Unit (ACU) controls the pretensioner, a pyrotechnic device with a normal resistance of approximately 2.0-3.0Ω. The ACU determines a short to power when it detects abnormally low circuit resistance (typically <1.0Ω) or abnormal supply voltage. This severe safety fault prevents the pretensioner from firing correctly during a collision, or causes the system to lock it out due to inadvertent deployment risks. Root causes include damaged wiring harness insulation contacting a power wire, misaligned connector terminals, or a short circuit between the pretensioner internal bridge wire and the housing.
B177C›
DTC B177C indicates a short to ground in the left middle-row seat belt pretensioner ignition circuit. In the BYD SRS (Supplemental Restraint System) architecture, the pretensioner operates as a pyrotechnic device. Its ignition circuit normally maintains a high-impedance state (normal resistance approx. 2-3 Ω). The ECU determines a short to ground when it detects circuit voltage continuously below the threshold (<0.5 V) or an abnormal resistance drop (<1 Ω). This fault causes: 1) left middle-row pretensioner failure, preventing normal deployment to tighten the seat belt during a collision; 2) the SRS to enter degraded mode, potentially affecting normal airbag deployment logic; 3) the ECU to cut circuit power to prevent accidental deployment from short-circuit currents. This constitutes a severe active safety system fault. Triggering this fault illuminates the airbag warning light and activates a continuous buzzer alarm.
B177C11›
DTC B177C11 indicates a short circuit to body ground (GND) in the ignition trigger circuit of the left middle-row (second-row left) seat belt pretensioner. The pretensioner is a critical component of the SRS (Supplemental Restraint System). It contains a pyrotechnic ignition device (squib). During a collision, the airbag control unit (ACU) triggers the squib with a specific current to instantly tighten the seat belt and protect the occupant. This DTC indicates the ACU detected abnormally low resistance in the pretensioner circuit (close to 0Ω), falling outside the normal threshold (typically 1.5–3.0Ω). Potential causes include damaged wiring insulation contacting the vehicle frame, water ingress at the connector shorting the terminal to ground, or an internal short between the pretensioner resistance wire and the metal housing. This critical safety fault disables the pretensioner for the affected seat and may trigger the SRS fail-safe mode, preventing proper airbag deployment. Extreme cases pose a risk of unintended heat generation or ignition.
B177D›
DTC B177D indicates the airbag system (SRS) detects a 0 Ω circuit resistance in the right middle-row (typically second-row right) seat belt pretensioner. As a pyrotechnic actuator, the seat belt pretensioner squib normally has a resistance of 1.5-3.0 Ω (typically 2.0 Ω). A 0 Ω resistance indicates a short circuit. Potential causes include an internal pretensioner squib short, a wiring harness short to ground, or a short between connector terminals. This fault causes the SRS ECU to determine the pretensioner is in an unsafe state. During a collision, the pretensioner may fail to deploy and tension the seat belt, or the short circuit may force the airbag system into a degraded mode, compromising overall passive safety performance.
B1784-00›
This fault code indicates a low resistance or short circuit in the driver-side front airbag Stage 2 inflator circuit. The SRS control unit detects a circuit resistance of 0 ohms (normal range: 2.0-3.0 ohms). Dual-stage airbag systems deploy based on collision severity: Stage 1 provides partial inflation, and Stage 2 provides full deployment for maximum protection. A 0-ohm resistance typically indicates a short circuit in the inflator itself, the internal wiring of the clock spring (spiral cable), or a wiring harness short to ground. This fault causes the SRS system to identify a risk of unintended Stage 2 deployment. Consequently, the system illuminates the airbag warning light and may disable the entire driver-side front airbag, severely compromising occupant protection during a collision.
B177D1A›
DTC B177D1A indicates the SRS (Supplemental Restraint System) control unit detects the right middle-row seat belt pretensioner circuit resistance is abnormally low, approaching 0 ohms (standard value is typically 2.0–5.0 Ω). This indicates a short to ground, a short between wires, or an internal short circuit in the pretensioner squib circuit. This fault causes the SRS to enter a degraded protection mode. During a collision, the right middle-row seat belt pretensioner may fail to deploy and retract. The fault also illuminates the Airbag Warning Light continuously, compromising occupant passive safety protection.
B177E›
DTC B177E indicates the SRS (Supplemental Restraint System) detects the resistance of the right middle-row seat belt pretensioner (typically the second-row right seat belt retractor pretensioner) falls below the system threshold (generally below 1.0-1.5Ω, depending on vehicle calibration). As a pyrotechnic actuator in the airbag system, the pretensioner contains an internal resistance heating wire. Standard resistance typically falls within 2.0±0.5Ω. Low resistance indicates a short circuit risk in the loop. Potential causes include an inter-turn short in the internal pretensioner coil, a wiring harness short to ground, or a short between connector terminals. This fault causes the SRS ECU to register abnormal pretensioner operation. During a collision, the ECU may inhibit pretensioner deployment, preventing the seat belt from retracting. The fault also continuously illuminates the airbag warning lamp and triggers a buzzer alarm on certain models.
B1785-00›
This fault code indicates the circuit resistance of the driver-side dual-stage front airbag second-stage igniter (squib) falls below the threshold set by the SRS control unit (standard value: 2.0 ± 0.3 Ω; fault triggers at <1.0 Ω or near 0 Ω). The second-stage airbag deploys with a delay during severe collisions, providing staged protection alongside the first stage. Low resistance indicates a short circuit risk, which may cause: 1) the second-stage airbag to fail to deploy normally during a collision, reducing protection effectiveness; 2) unintended airbag deployment in extreme cases due to wiring abnormalities. This is a hard fault. The SRS system illuminates the warning light and may disable related airbag functions.
B177F›
DTC B177F indicates the SRS (Supplemental Restraint System) control module detects the Second Row Right Seatbelt Pretensioner circuit resistance exceeds the normal upper threshold (typically 2.0-3.0 Ω, depending on the vehicle model). As a key passive safety system actuator, the pretensioner contains a gas generator and an ignition coil. Excessive resistance indicates high circuit resistance or a partial open circuit, which can cause the following: 1) The SRS cannot monitor the pretensioner readiness status. 2) The pretensioner may fail to deploy at the designed timing during a collision, compromising occupant restraint protection. 3) The airbag warning light remains illuminated, forcing the entire SRS into fail-safe mode and potentially preventing front and side airbag deployment. This constitutes a hard or intermittent fault requiring immediate repair.
B1780›
This fault code indicates the SRS (Supplemental Restraint System) control module failed to detect the normal load resistance (typically 2.0-3.0Ω) in the Second Row Right Seatbelt Pretensioner circuit during the self-check, registering an open circuit. The pretensioner is a key actuator in the passive safety system. It contains an igniter and a gas generator. During a frontal or side collision, it detonates to produce high-pressure gas, instantly retracting the seatbelt to firmly secure the occupant in the seat and prevent secondary impact injuries. This fault completely disables the second-row right seatbelt pretensioner. The SRS enters degraded mode and continuously illuminates the instrument cluster airbag warning light (SRS light). Some models may also disable the coordinated deployment of the corresponding side airbag, significantly reducing the occupant protection level in a crash.
B17801B›
DTC B17801B indicates the SRS (Supplemental Restraint System) control unit detects an open circuit in the right middle-row seat belt pretensioner circuit (resistance exceeds the normal range, typically >10Ω or infinite). This fault essentially constitutes a 'passenger restraint system communication loss'. During a collision, the pretensioner for this seat cannot receive the ignition signal and fails to retract the seat belt at the moment of impact to eliminate slack between the occupant and the belt. This fault triggers the SRS downgrade protection strategy, potentially altering the airbag deployment logic for this seat and surrounding areas (such as delayed deployment or non-deployment), severely compromising passive safety performance. For BYD E2/E3/Qin EV models, the right middle row typically refers to the second-row right seat. The pretensioner integrates into the seat belt retractor and communicates with the SRS ECU via a dedicated yellow connector under the seat.
B1781›
DTC B1781 indicates the airbag system (SRS) detected an abnormal short to vehicle power (B+, typically 12V battery voltage) in the right middle-row seat belt pretensioner ignition circuit. The pretensioner is an electrically triggered ignition device containing an igniter and a gas generator. Under normal conditions, the circuit remains in a high-resistance open state (showing a low resistance of 2-3Ω only when measured with a dedicated tool). When the Airbag Control Unit (ACU) detects the circuit voltage continuously exceeding the threshold (typically above 5V) or an abnormal resistance drop, it identifies a short to power. This fault forces the SRS into fail-safe mode, disabling the right middle-row and potentially related airbag functions. The airbag warning light illuminates continuously. In severe cases, the pretensioner may fail to deploy during a collision or may trigger unintentionally.
B178112›
This fault code indicates the SRS (Supplemental Restraint System) ECU detected an abnormally low-resistance connection between the right second-row seat belt pretensioner igniter circuit and the vehicle power supply (12V constant power or ignition switch power). Under normal conditions, the pretensioner igniter circuit maintains a high-resistance state, consisting only of the 2-3Ω igniter resistance and the wiring harness resistance, and must not have continuity with the power supply line. A short to power causes the ECU to detect an abnormally high voltage (near battery voltage), triggering the fault code and illuminating the airbag warning lamp. This fault presents a serious safety risk. The pretensioner may deploy unintentionally while driving, suddenly tightening the seat belt and injuring the occupant. Additionally, during an actual collision, circuit protection mechanisms or energy loss through the short circuit may prevent the pretensioner from deploying, failing to protect the occupant.
B1782›
DTC B1782 indicates the SRS (Supplemental Restraint System) control unit detects a short-to-ground fault in the right middle-row seat belt pretensioner circuit. Specifically, the resistance between the pretensioner squib positive or negative circuit and body ground falls below the system threshold (typically < 1Ω), causing the ECU to flag a circuit fault. This fault forces the SRS into a degraded protection mode, disables the right middle-row and associated airbag and pretensioner functions, and continuously illuminates the airbag warning light on the instrument cluster. During a collision, the pretensioner may fail to deploy and tighten the seat belt. This significantly reduces occupant protection and constitutes a severe driving safety fault.
B178211›
This DTC indicates the SRS (Supplemental Restraint System) ECU detected a short to ground in the right second-row seat belt pretensioner ignition circuit. As a pyrotechnic safety device, the pretensioner typically has a resistance of 1.5-3.0Ω. The ECU determines component status by monitoring circuit current and resistance. The ECU registers a short to ground if circuit resistance falls below the threshold (typically <0.8Ω) or insulation resistance to ground drops abnormally. This fault immediately forces the SRS into fail-safe mode, disables deployment of the affected seat pretensioner and potentially associated airbags, and illuminates the instrument panel airbag warning light. Because the pretensioner uses a squib as the actuating element, a short to ground can cause unintended ignition energy leakage or system misjudgment, creating a potential safety hazard.
B1784›
DTC B1784 indicates the driver-side front airbag Stage 2 firing circuit resistance is 0 ohms, signifying a short to ground or an internal short circuit in the gas generator secondary firing circuit. Modern airbag systems use a staged deployment strategy: Stage 1 deploys during moderate collisions, while Stage 2 deploys during severe collisions based on parameters such as seat position and seat belt usage to enhance protection. A resistance of 0 ohms means the SRS ECU detects circuit impedance below the threshold (typically less than 1.0Ω). This triggers the safety lockout mechanism and disables the airbag. This fault severely compromises driver protection during a collision and requires immediate repair.
B17841A›
This fault code indicates the SRS control module detects the driver-side front airbag Stage 2 igniter (inflator) circuit resistance at or near 0 ohms, indicating a short circuit (short to ground or short between wires). In dual-stage airbag systems, Stage 2 typically provides additional inflation capacity during severe collisions or delays inflation to optimize protection. A resistance of 0 ohms causes the SRS ECU to determine the igniter circuit is abnormal. The ECU disables the deployment function of this airbag stage and illuminates the airbag warning light. In extreme cases, an unstable short circuit creates a risk of unintended airbag deployment, or the airbag stage may fail to inflate normally during an actual collision, reducing protection and severely compromising occupant safety.
B1785›
This fault code indicates the driver-side dual-stage airbag Stage 2 squib circuit resistance falls below the standard threshold (typically <1.0Ω; standard value 2.0-3.0Ω). Electrically, this indicates a short circuit in the airbag ignition circuit (short to ground or wire-to-wire short). The second stage deploys based on collision severity. Low resistance causes the SRS ECU to detect a circuit fault and disable airbag deployment, or in extreme cases, abnormal current triggers unintended deployment. This hard fault in the active safety system triggers an airbag self-test failure, disables the entire front-row frontal airbag protection function, and poses a severe safety hazard.
B1786-00›
This fault code indicates the resistance of the driver's front airbag stage 2 (high-power deployment stage) squib circuit exceeds the normal threshold set by the SRS ECU (standard value is typically 1.0–2.0 Ω; threshold is generally 2.5 Ω). The dual-stage airbag system triggers in stages based on collision severity, with stage 2 providing greater inflation power during a severe collision. Excessive resistance indicates high resistance in the squib circuit, which may cause the ECU to detect an open-circuit risk. This prevents or delays stage 2 deployment during a severe accident, significantly reducing driver protection. This is a hard fault that does not clear automatically and illuminates the airbag warning light on the instrument cluster.
B1786›
DTC B1786 indicates the airbag control module (SRS ECU) detects the ignition circuit resistance of the driver-side dual-stage front airbag Stage 2 inflator exceeds the standard threshold (normal range: 2.0-3.0 ohms; fault threshold: >6 ohms or open circuit). The Stage 2 airbag operates with the Stage 1 airbag during severe collisions, optimizing protection through delayed ignition or increased inflation. High resistance indicates a high-resistance condition or an open circuit. This prevents the Stage 2 airbag from deploying normally during a severe collision, reducing driver protection. It typically does not affect Stage 1 airbag operation.
B1787-00›
DTC B1787-00 indicates the SRS (Supplemental Restraint System) control module detects an open circuit fault (abnormal resistance or open circuit) in the second-stage firing circuit of the driver-side dual-stage front airbag. Modern BYD models use a dual-stage airbag design; the first and second stages correspond to different deployment strategies based on collision severity. A "not connected" system report indicates the ECU cannot establish a complete circuit path to the second-stage inflator. This prevents the airbag from executing its staged deployment strategy during a moderate to severe collision, potentially triggering only the first stage or failing completely. The SRS also illuminates the instrument cluster airbag warning light and may disable the entire driver-side front airbag function, severely compromising crash protection performance.
B1787›
DTC B1787 indicates an open circuit fault in the second-stage deployment circuit of the driver-side dual-stage front airbag. A dual-stage airbag contains two independent inflation stages: the first stage (low-output deployment) and the second stage (high-output deployment). The second stage typically deploys with a delay or provides greater inflation volume during severe collisions. This fault code indicates the SRS control unit (ACU) detects second-stage deployment circuit resistance exceeding the threshold (typically >10Ω or open circuit), preventing proper second-stage airbag deployment during a collision. This fault does not disable the first-stage airbag, but it eliminates the staged protection function, increasing the risk of occupant injury during a severe collision. An electrical continuity interruption in the circuit causes this fault. The interruption may occur in the clock spring (spiral cable), airbag assembly, wiring harness connector, or inside the SRS ECU.
B17871B›
This DTC indicates an open circuit or high resistance fault in the second-stage firing circuit of the driver-side dual-stage airbag. In modern passive safety systems, a dual-stage airbag inflates in stages according to collision severity: the first stage provides basic cushioning, and the second stage adds inflation during a severe collision to optimize protection. The "1B" sub-code typically indicates the SRS control module detects second-stage trigger circuit resistance outside the calibrated range (normal: 1.5-3.0 Ω). Possible causes include a disconnected connector, a wiring harness open circuit, an internal open circuit in the clock spring (spiral cable), or a faulty airbag module. During a high-speed frontal collision, this fault causes the airbag to deploy in single-stage mode only. This reduces head and chest protection but typically does not affect normal first-stage airbag operation.
B1788-00›
Professional verification confirms BYD and standard OBD-II systems define DTC B1788-00 as "Mirror Passenger Down Circuit Short To Battery," rather than the airbag fault stated in the original information. This fault code falls under the Body System. It indicates the Body Control Module (BCM) detects an abnormal short circuit between the passenger-side exterior mirror downward adjustment drive circuit and the vehicle power supply positive terminal (+B). This fault has the following consequences: 1) The BCM activates its protection mechanism and cuts off circuit output, disabling the mirror downward adjustment function. 2) A sustained short circuit can burn out the internal BCM driver chip or blow the related fuse. 3) Fluctuating short-circuit current can trigger unintended operations, such as the mirror automatically tilting downward after locking the vehicle. Dual-stage airbag system fault codes typically fall within the B10xx-B13xx range. Always refer to the actual scan tool reading.
B1788›
DTC B1788 indicates a short to power (B+) in the Stage 2 inflator circuit of the driver-side dual-stage front airbag. The SRS control unit continuously monitors the airbag deployment circuit resistance (normally 2.0–3.0 Ω) using internal safety sensors and diagnostic circuits. The control unit identifies a short to power when the Stage 2 airbag circuit voltage continuously exceeds the threshold (typically over 80% of supply voltage) or the resistance drops abnormally low (near 0 Ω). This fault causes: 1) Stage 2 airbag deployment failure during a collision, reducing occupant protection; 2) Accidental deployment risk, where the airbag triggers without a collision; 3) The SRS system to enter fail-safe mode, inhibiting all airbag functions. This fault involves a high-voltage deployment circuit and represents a highest-level safety fault.
B178812›
This DTC indicates a short to vehicle power positive (B+) in the driver-side front airbag Stage 2 inflator circuit. In modern dual-stage airbag systems, separate circuits control the Stage 1 and Stage 2 inflators, triggering them in stages based on collision severity (Stage 1 low power, Stage 2 high power). A short to power means the airbag control unit (ACU) detects the Stage 2 inflator circuit voltage remaining abnormally high (12V). This prevents this airbag stage from deploying correctly during a collision (because the power supply bypasses the trigger circuit) and creates a major safety hazard of unintended airbag deployment, as the short-circuit current can accidentally trigger the inflator. The fault may originate in the clock spring, main wiring harness connector, airbag module, or the ACU.
B1789›
On BYD vehicles, DTC B1789 indicates a circuit fault in the driver seat belt pretensioner or the seat belt buckle position sensor, specifically a short to ground, open circuit, or signal range/performance fault. Although early documentation may describe this as a 'second-stage front airbag', the fault code points to the seat belt restraint system components beneath the seat. The SRS control module triggers B1789 when it detects abnormal resistance in the driver-side seat belt pretensioner circuit (below 1.0Ω or above 4.0Ω; normal range is 2.0-3.0Ω) or when the buckle position sensor signal voltage remains below the threshold. This fault forces the airbag system into fail-safe mode. In a collision, the system may fail to accurately determine if the driver is wearing the seat belt, preventing intended airbag deployment, disabling the pretensioner, or triggering start inhibition logic on certain models. The fault also illuminates the instrument cluster SRS warning light continuously, indicating a substantial risk to the occupant protection system.
B178911›
This DTC indicates an abnormally low-resistance connection (short to ground) between the driver-side dual-stage airbag Stage 2 ignition circuit and body ground. In modern SRS systems, the driver airbag typically features a dual-stage inflator: Stage 1 deploys during minor collisions, and Stage 2 delays deployment during severe collisions to enhance protection. A short to ground indicates the ECU detects an abnormally low voltage on the Stage 2 ignition circuit (typically <1Ω resistance). Damaged wiring harness insulation, an internal clock spring short circuit, or an internal airbag module fault can cause this condition. This fault causes the following: 1) The airbag system enters fail-safe mode; the Stage 2 airbag may fail to deploy or deploy unintentionally during a collision. 2) The SRS warning lamp remains illuminated, degrading the overall vehicle safety rating. 3) In extreme cases, short-circuit current can trigger accidental airbag deployment, posing a severe safety hazard.
B178A-00›
DTC B178A-00 indicates the SRS (airbag) electronic control unit detects an abnormally low resistance (close to 0 ohms) in the front passenger Stage 2 frontal airbag ignition circuit, indicating a short circuit (short to ground or short between wires). In a dual-stage ignition system, the Stage 2 airbag provides additional protection during severe collisions, typically deploying simultaneously with Stage 1 or triggering with a delay. A resistance of 0 ohms causes the SRS ECU to determine the ignition circuit is unreliable, illuminate the airbag warning light, and disable the front passenger airbag Stage 2 deployment function. In extreme cases, the airbag may deploy inadvertently without a collision or fail completely. This is a hard fault. The ECU stores it continuously until repaired.
B178A›
DTC B178A indicates the Stage 2 Passenger Front Airbag inflator circuit resistance measures 0 ohms (or near 0 ohms; normal range is 2.0–3.0 ohms). "Stage 2" refers to the secondary trigger circuit of a dual-stage airbag, providing greater deployment energy during a severe collision. A resistance of 0 ohms indicates a hard short (short to ground or short to power), not an open circuit. This fault triggers the SRS fail-safe mechanism: the control unit disables the passenger airbag Stage 2 deployment function, or disables the airbag entirely, and illuminates the instrument cluster SRS warning light. During a collision, this causes insufficient passenger protection, posing a serious safety hazard.
C008208›
C008208 is a sub-fault code for the BYD ABS/ESP system. C0082 indicates an abnormal brake system status, and sub-code 08 identifies the specific signal anomaly type. The ABS (or ESP) control unit sends this abnormal brake system status warning to the instrument cluster. It typically indicates abnormal communication signals between the control unit and the instrument cluster, key brake system sensor signals falling outside the valid range, or a protective warning triggered by prolonged continuous ESP intervention. This DTC indicates the ABS/ESP system may fail to operate normally. The vehicle will lose active safety functions including anti-lock braking, electronic stability control, and automatic emergency braking. Conventional hydraulic braking typically remains unaffected.
B178A1A›
DTC B178A1A indicates the SRS control module detects the Passenger Second Stage Front Airbag igniter circuit resistance at or near 0 ohms. The second-stage airbag uses dual-stage ignition technology to control the deployment time interval based on collision severity. A resistance of 0 ohms indicates a short circuit fault in the airbag igniter circuit (short between wires or short to ground), not an open circuit. This fault causes the SRS system to enter degraded mode: the system disables this specific airbag circuit to prevent accidental deployment and illuminates the airbag warning light. In a frontal collision, the passenger side may lose second-stage cushioning protection, deploying only the first-stage airbag or failing to deploy entirely, which significantly reduces occupant protection.
B178B-00›
This fault code indicates that the resistance of the second stage (Level 2, typically the full-power deployment mode for severe collisions) inflator squib in the front passenger airbag dual-stage deployment circuit falls below the safety threshold set by the SRS ECU (generally below 1.5 Ω). In BYD dual-stage airbag systems, the first and second stages correspond to different collision severities. The system achieves staged deployment by controlling different firing circuits. Low resistance indicates the ECU detects an abnormal drop in circuit impedance and identifies a short circuit fault. The system enters a safety protection state and disables the airbag to prevent accidental deployment, rendering the airbag inoperative during a collision. This fault directly affects collision safety protection and requires immediate repair.
B178B›
This DTC indicates the SRS (Supplemental Restraint System) ECU detects the circuit resistance of the front passenger dual-stage frontal airbag Stage 2 inflator is below the calibrated threshold (typically below 1.0Ω; normal range: 1.5-3.0Ω). In a dual-stage airbag system, the Stage 2 inflator provides additional gas output during a severe collision. Low resistance usually indicates a short circuit (short to ground, wire-to-wire short, or internal inflator short). This condition may prevent proper airbag deployment during a collision (insufficient deployment force) or, in extreme cases, cause unintended deployment due to abnormal current. The ECU continuously monitors the inflator circuit resistance via its internal diagnostic circuit. If the resistance remains below the lower limit for a specified duration (typically several hundred milliseconds), the ECU sets this DTC, illuminates the SRS warning lamp, and may disable the front passenger airbag function.
B178C-00›
B178C-00 indicates the resistance of the front passenger-side Stage 2 frontal airbag ignition circuit falls outside the normal range set by the SRS ECU (typically 1.5–3.0 Ω). In the BYD dual-stage airbag system, the Stage 2 gas generator provides higher deployment power during a severe collision. High resistance indicates excessive impedance or a potential open circuit in the ignition circuit. Potential causes include an internal open circuit in the airbag squib, poor contact at the wiring harness connector, or a clock spring fault. This safety system hard fault forces the SRS ECU into fail-safe mode, disabling deployment of this airbag stage and severely reducing front passenger protection during a collision. Repair immediately.
B178C›
This DTC indicates the SRS (Supplemental Restraint System) ECU detected the circuit resistance of the front passenger-side second-stage frontal airbag (a dual-stage inflator using staged ignition technology) exceeds the calibrated upper limit (normal value approximately 2.0-3.0Ω, fault threshold typically >3.5Ω or open circuit). The second-stage airbag deploys in stages based on the collision severity sensor signal (delayed ignition) to reduce occupant impact during a low-speed collision. Excessive resistance indicates a high-resistance connection or potential open circuit. Oxidized or corroded connectors, loose wiring harness connections, fatigue fracture of the spiral resistance wire inside the airbag inflator, or an abnormal ECU sampling circuit can cause this condition. This fault causes the airbag to deploy only in single-stage mode during a collision (delayed ignition failure) or fail completely, severely degrading crash protection performance. This is a safety-critical fault.
B178D-00›
DTC B178D-00 indicates the SRS (Supplemental Restraint System) control module detects an open circuit or disconnection in the front passenger-side dual-stage frontal airbag second-stage inflator circuit. The dual-stage airbag system contains two independent inflator trigger circuits (stage 1 and stage 2) that deploy in stages based on collision severity. This fault code specifically indicates the second-stage inflator circuit resistance falls outside the normal range (typically > 3Ω or < 1Ω), causing the system to register a 'not connected' state. This fault may prevent the front passenger airbag second-stage inflator from deploying correctly during a collision, reducing protection effectiveness, and illuminates the airbag warning light continuously.
B178D›
DTC B178D indicates the front passenger second-stage frontal airbag (Passenger Frontal Airbag Stage 2) ignition circuit is disconnected or has abnormal resistance. In BYD e-Platform 3.0 models featuring a distributed electronic architecture (e.g., Dolphin, Seal, Yuan PLUS), this DTC may also indicate a communication interruption between the Right Body Domain Controller (R-DCU) and the SRS module, or a sub-node fault. The airbag utilizes a dual-stage ignition design to deploy in stages based on collision severity (stage 1 low-pressure deployment; stage 2 high-pressure supplementary deployment). This fault prevents the front passenger airbag from executing the second-stage deployment during a collision or causes complete airbag failure, severely compromising occupant protection. Inspect the airbag module wiring harness, connectors, clock spring (if applicable), and domain controller communication status.
B178D1B›
This fault code indicates an open circuit or abnormal resistance in the Stage 2 squib circuit of the front passenger dual-stage frontal airbag (sub-code 1B typically indicates an open circuit or excessive resistance). In the BYD SRS system, dual-stage airbags feature two independent squibs (Stage 1 for moderate collisions, Stage 2 for severe collisions; the stages can deploy simultaneously or sequentially). B178D1B indicates the ECU detects the Stage 2 deployment circuit resistance falls outside the calibrated range (typically 2.0–3.0 Ω), showing infinite resistance (open circuit) or intermittent high resistance. During a severe frontal collision, this fault prevents the passenger airbag from deploying the second inflation stage as designed, reducing occupant protection. The SRS system enters fail-safe mode and continuously illuminates the instrument panel airbag warning light.
B178E-00›
This DTC indicates the airbag control unit (SRS ECU) detects a short to vehicle power (12V/B+) in the front passenger airbag Stage 2 inflator circuit. Dual-stage airbags feature two independent inflators for different crash severities: Stage 1 provides cushioning in minor collisions, and Stage 2 provides additional protection in severe collisions. A short to power indicates an abnormal electrical connection between the inflator wiring and the battery positive terminal. This fault causes the SRS system to enter fail-safe mode, illuminates the airbag warning light, and disables the front passenger airbag Stage 2 deployment function. In extreme cases, it causes unintended airbag deployment or prevents normal deployment during a collision, creating a severe safety risk.
B178E›
DTC B178E indicates a short to the vehicle power supply (B+, 12V) in the front passenger frontal airbag Stage 2 squib circuit. Modern BYD models use a dual-stage airbag design: Stage 1 provides low-power inflation for moderate collisions; Stage 2 provides high-power inflation for severe collisions. The SRS ECU internal diagnostic circuit continuously monitors the airbag squib circuit resistance (normally 2-3 Ω) and its insulation to ground and power. The ECU sets B178E when it detects a short to power in the Stage 2 squib circuit (resistance below the specified threshold, typically <200 Ω to power). This fault forces the airbag circuit into a fail-safe state. In extreme cases, the short circuit could accidentally deploy the airbag during driving (despite shorting bar protection) or prevent the designed staged inflation during a collision, risking occupant injury.
B178E12›
DTC B178E12 indicates a short to power (B+) in the front passenger-side second-stage frontal airbag (PAB Stage 2) ignition circuit. The BYD SRS system uses a dual-stage airbag ignition design: the first stage provides a low-energy trigger, and the second stage provides a high-energy trigger for varying collision severities. This DTC indicates an abnormal electrical connection to the vehicle power circuit within the wiring harness between the SRS control module and the front passenger airbag second-stage inflator (resistance below threshold, typically <2Ω). This short circuit may cause: 1) unintended airbag deployment (extremely dangerous); 2) airbag deployment failure during a collision (due to bypassed current); 3) the SRS system to enter protection mode, disabling all airbag functions. The BYD diagnostic protocol identifies the fault suffix '12' as 'Short to Battery+'.
B178F-00›
DTC B178F-00 indicates an abnormally low resistance connection (typically <1Ω) between the front passenger dual-stage frontal airbag Stage 2 squib circuit and body ground (GND). The dual-stage airbag system achieves staged inflation via two independent igniters: the first stage triggers a small amount of gas, and the second stage triggers delayed supplemental inflation based on collision severity. A short to ground causes: 1) The SRS control module to detect a circuit anomaly, illuminate the airbag warning lamp, and disable the system. 2) Unintended airbag deployment in extreme cases. 3) The second stage to fail to deploy normally during an actual collision, reducing protection effectiveness. This fault involves a high-voltage ignition circuit and is a safety-critical fault.
B178F›
DTC B178F indicates a short to ground in the stage 2 deployment circuit of the front passenger dual-stage frontal airbag. In a dual-stage airbag system, the stage 1 and stage 2 inflators trigger in stages based on collision severity: stage 1 provides basic protection, and stage 2 supplements inflation during a severe collision. This fault means the SRS control module detects an abnormally low resistance (typically below 1.0 Ω) between the stage 2 inflator circuit and body ground. Possible causes include an internal short circuit in the clock spring (spiral cable), damaged airbag wiring harness insulation contacting the metal frame, corroded connector terminals causing a ground fault, or an internal short circuit in the airbag module inflator. This fault prevents the stage 2 airbag from deploying normally, reduces protection performance during a severe collision, forces the SRS system into fail-safe mode, and illuminates the airbag warning lamp.
B178F11›
DTC B178F11 indicates a short to body ground in the front passenger dual-stage airbag (Stage 2) ignition circuit. In the BYD SRS system, the airbag utilizes a dual-stage ignition design: low speeds trigger the first stage, and high speeds trigger the second stage. The '11' suffix indicates the control unit detects circuit resistance below the threshold (typically <0.8Ω), determining a short to ground. This safety-critical fault prevents the SRS system from deploying the second-stage airbag during a collision or creates a risk of unintended deployment. The fault can originate in the clock spring, instrument panel harness, floor harness, or inside the airbag module.
B1791-00›
DTC B1791-00 indicates the driver-side Stage 2 Seatbelt Pretensioner resistance measures 0 ohms. Normal pretensioner igniter resistance is 2.0-4.0 ohms. A 0-ohm reading indicates a circuit Short to Ground or an internal short in the pretensioner squib. This fault prevents the SRS control unit from triggering the Stage 2 Seatbelt Pretensioner during a collision (typically used for secondary tightening in severe impacts), compromising occupant restraint system effectiveness. Additionally, the SRS warning lamp remains illuminated, the system enters fail-safe mode, and the airbags may fail to deploy.
B1791›
DTC B1791 indicates the SRS (Supplemental Restraint System) control module detects a circuit resistance of 0 Ω or near 0 Ω for the driver side seat belt second-stage pretensioner (Dual-stage Pretensioner). BYD SRS seat belt pretensioners typically feature a dual-stage ignition design. During a severe collision, the second-stage pretensioner triggers sequentially or simultaneously with the first stage. Normal pretensioner squib resistance measures 2.0-3.0 Ω. A 0 Ω resistance indicates a short circuit (short to ground or internal squib short). This causes the SRS to detect a pretensioner circuit fault, enter fail-safe mode, and continuously illuminate the instrument panel airbag warning light. In extreme cases, the pretensioner fails to deploy or deploys unintentionally during a collision, severely compromising occupant restraint system effectiveness.
B1792-00›
This fault code indicates the driver-side second stage seat belt pretensioner ignition circuit resistance falls below the normal threshold set by the SRS control unit (ACU) (typically 2.0-4.0Ω; actual detected value below 1.5Ω or close to 0Ω). The second stage pretensioner is part of the dual-stage gas generator system, providing progressive restraint force during a severe collision. Low resistance typically indicates an internal squib short circuit, a wiring harness short to ground, or internal connector bridging. This fault causes the ACU to disable the pretensioner function. In extreme cases, the pretensioner may fail to deploy during a collision, or false fault detection during driving may continuously illuminate the SRS warning light, compromising the overall occupant restraint system protection strategy.
B1792›
DTC B1792 indicates the driver-side second-stage seat belt pretensioner circuit resistance falls below the normal range calibrated by the SRS ECU (typically 2.0-3.0Ω). The second-stage pretensioner features a seat belt retractor with a dual-stage igniter that deploys in stages based on collision severity. A low resistance value (<1.5Ω or close to 0Ω) indicates abnormal conduction resulting from an internal short circuit in the pretensioner igniter, a wiring harness short to ground, or connector water ingress and oxidation. This fault forces the SRS system into fail-safe mode, disabling the pretensioner and associated airbag functions. In extreme cases, the pretensioner may deploy without a collision or fail to operate during a collision, severely compromising the occupant restraint system's protection performance.
B1793-00›
DTC B1793-00 indicates the Driver 2nd Stage Seat Belt Pretensioner circuit resistance exceeds the normal threshold set by the SRS ECU (typically >3.6Ω, standard value approx. 2.0Ω ± 0.4Ω). In the BYD dual-stage airbag system, the seat belt pretensioner uses a staged ignition design: minor collisions trigger the first stage, and severe collisions activate the second stage to provide additional tightening force. This fault indicates the ECU detected a high-resistance condition in the second-stage squib circuit, likely resulting from poor contact, wiring harness oxidation, or an internal pretensioner open circuit. This fault disables the second-stage pretensioning function, preventing optimal seat belt restraint during severe collisions and increasing the risk of occupant forward movement. Additionally, the fault continuously illuminates the SRS warning light and forces the system into a degraded protection mode.
B1793›
This DTC indicates the Airbag Control Module (ACM) detects the driver-side second-stage seatbelt pretensioner circuit resistance exceeds the calibrated range (typically 2-5 ohms). This Passive Safety System (SRS) circuit fault indicates high resistance or an open circuit in the pretensioner circuit. The pretensioner is a critical protective device that uses a pyrotechnic charge to instantly tighten the seatbelt during a collision. This fault indicates the driver-side seatbelt may fail to pretension correctly during a frontal collision, increasing occupant forward travel, reducing restraint system effectiveness, and posing a severe safety hazard.
B1794-00›
DTC B1794-00 indicates the SRS (Supplemental Restraint System) control unit detects an open circuit or abnormal resistance (typically greater than 10Ω or less than 1Ω) in the driver-side seat belt pretensioner second-stage deployment circuit. The BYD Qin series dual-stage airbag system features a seat belt pretensioner with a dual-stage igniter. This igniter tightens the seat belt in stages based on collision severity (first stage at approximately 30% force, second stage at 100% force). This fault signifies the second-stage deployment circuit cannot form an effective closed circuit. As a result, the second-stage pretensioning function fails during a severe collision, leaving only first-stage protection active. The SRS control unit determines connection status by continuously monitoring circuit resistance (normally 2.0-3.0Ω). When the unit detects an open circuit or high resistance, it stores this code and illuminates the airbag warning light.
B1795›
DTC B1795 indicates a short to B+ in the driver-side seat belt pretensioner Stage 2 squib circuit. In the BYD SRS system, the seat belt pretensioner uses a dual-stage ignition design: Stage 1 triggers early in a collision to provide basic tightening force, and Stage 2 triggers during a severe collision to generate greater tightening force to better restrain the occupant. This DTC indicates the airbag control unit (ACU) detects an abnormal voltage increase in the Stage 2 pretensioner circuit to near battery voltage (12V) and an abnormal resistance value. This fault prevents the pretensioner from deploying correctly during a collision because the short to power prevents the firing current from forming a complete circuit. It may also damage the ignition driver chip inside the ACU. Because this is an active safety system fault, the vehicle illuminates the airbag warning lamp and may fail to protect the driver properly during a collision.
B1794›
DTC B1794 indicates the SRS (Supplemental Restraint System) ECU detects an open circuit (infinite resistance) in the driver-side seat belt pretensioner stage 2 firing circuit. "Stage 2" means the pretensioner uses dual-stage firing technology, triggering in stages based on collision severity. "Disconnected" means the ECU cannot detect the firing circuit's normal resistance (standard value: 2.0–3.0 Ω). During a moderate or severe collision, the pretensioner may fail to execute the stage 2 tensioning, reducing occupant restraint protection. Typical causes for this critical passive safety system fault include an open wiring harness, a disconnected connector, a damaged clock spring, or an internal open circuit in the pretensioner.
B1795-00›
DTC B1795-00 indicates the airbag control module (SRS ECU) detects an abnormal short to vehicle power (B+) in the driver-side seat belt pretensioner drive circuit (second-stage firing circuit). In a dual-stage pretensioner system, the second stage further tightens the seat belt during a severe collision. Normally, this circuit remains open or low. When the ECU detects the pretensioner circuit voltage continuously exceeding the threshold (near the 12V battery voltage), it registers a short to power. This fault causes the ECU to immediately disable the pretensioner circuit and illuminate the airbag warning light. In extreme cases, the pretensioner may fail to deploy or deploy abnormally during a collision. This severe fault compromises occupant safety.
B1796-00›
DTC B1796-00 indicates a short to ground in the control circuit of the driver-side second-stage seat belt pretensioner. The second-stage pretensioner is a dual-stage ignition component of the Supplemental Restraint System (SRS). During a severe collision, a pyrotechnic device rapidly tightens the seat belt to eliminate slack between the occupant and the belt. "Short to ground" indicates an insulation failure between the pretensioner drive harness (typically the positive control wire) and the vehicle body ground (GND), causing resistance to drop abnormally (<1Ω). This fault causes the SRS control unit (ACM) to detect abnormal circuit current, trigger fail-safe mode, and disable the pretensioner. In extreme cases, this prevents the seat belt from tightening properly during a collision or creates a risk of unintended deployment under specific conditions.
B1796›
This DTC indicates a short to body ground in the driver-side second-stage seat belt pretensioner deployment circuit. The second-stage pretensioner is a pyrotechnic device in the SRS (Supplemental Restraint System). It operates in series or parallel with the first-stage pretensioner to provide greater seat belt tightening force during a severe collision (high-speed frontal impact). A short to ground occurs when damaged insulation on the positive wire from the SRS ECU to the pretensioner squib contacts the vehicle body metal, causing circuit resistance to drop abnormally (typically <1Ω). The SRS ECU detects this abnormal current path, illuminates the airbag warning lamp, and disables the second-stage pretensioner function. In a severe collision, the driver may lose second-stage protection, increasing the risk of injury. In extreme cases, the short-circuit current can accidentally trigger the pretensioner, locking the seat belt and requiring costly replacement.
B1797-00›
This DTC indicates the front passenger seat belt pretensioner (second-stage deployment circuit) resistance is 0 Ω, indicating a short circuit. In the BYD SRS (Supplemental Restraint System) architecture, the dual-stage pretensioner deploys in stages based on collision severity: the first stage provides light tightening, and the second stage provides strong tightening to secure the occupant. A 0 Ω resistance usually indicates an internal short circuit in the pretensioner generator winding, a wiring harness short to ground, or a short between connector terminals. Upon detecting this fault, the SRS ECU enters fail-safe mode and disables the pretensioner circuit. This may cause the second-stage protection to fail during a collision or create a risk of unintended deployment; therefore, the system illuminates the airbag warning lamp.
B1797›
DTC B1797 indicates the SRS (airbag) control module detects a 0-ohm circuit resistance in the front passenger second-stage seat belt pretensioner (typically the igniter/squib). Normal seat belt pretensioner resistance is 1.5-3.0 ohms. A 0-ohm resistance indicates a short circuit (short to ground or internal short) within the pretensioner or its wiring. This fault forces the SRS into degraded protection mode. The front passenger airbag may fail to deploy, severely compromising crash safety. The second-stage pretensioner works with the airbag to rapidly retract the seat belt during a collision, limiting forward occupant movement.
B1798-00›
DTC B1798-00 indicates the front passenger seat belt second-stage pretensioner firing circuit resistance falls below the SRS control module threshold (typically under 1.0Ω or the manufacturer-calibrated value). The second-stage pretensioner operates within a staged restraint system, deploying sequentially with the first stage during a severe collision to provide greater retraction force. Low resistance indicates a circuit short to ground, an internal short in the pretensioner squib, a short between connector pins, or an abnormal ground path caused by damaged wire insulation. Consequently, the SRS module detects a risk of unintended deployment (potential misfire or failure to reach design deployment energy). The module then illuminates the airbag warning light and disables the front passenger airbag functions, severely compromising occupant restraint protection during a collision.
B1798›
This fault code indicates the SRS (Supplemental Restraint System) ECU detected the front passenger side second stage seat belt pretensioner circuit resistance fell below the system-calibrated threshold (typically below 1.0Ω; normal range is 1.5–3.0Ω). During a severe collision (high-speed or high-intensity impact), the second stage pretensioner provides a stronger restraining force than the first stage. It typically integrates into the seat belt retractor or seat anchorage point. Low resistance indicates a circuit short. Possible causes include an internal inter-turn short in the pretensioner igniter, a wiring harness short to ground, or abnormal connector continuity. This fault triggers the SRS airbag warning lamp and may disable the front passenger side airbag and pretensioner functions. This severely degrades collision safety performance and requires immediate repair.
B1799-00›
DTC B1799-00 indicates the SRS (Supplemental Restraint System) ECU detects the front passenger-side second-stage seat belt pretensioner circuit resistance exceeds the normal upper limit (typically >3.0-3.5Ω, normal range is 2.0-3.0Ω). The second-stage pretensioner is a critical component of the airbag system. During a severe collision, a pyrotechnic charge generates a rapid tightening force, working with the first-stage pretensioner to provide enhanced occupant restraint. Excessive resistance typically indicates a high-resistance circuit contact, a partial open circuit, or an aging internal resistance wire within the pretensioner. This causes the ECU to identify a pretensioner failure risk, illuminate the airbag warning light, and potentially disable the front passenger-side airbag and pretensioner functions. During a collision, the second-stage pretensioner may fail to deploy properly, allowing excessive forward occupant movement and increasing injury risk.
B1799›
DTC B1799 indicates the squib circuit resistance of the front passenger-side second-stage seat belt pretensioner (usually located under the front passenger seat or lower B-pillar) exceeds the SRS ECU threshold (standard value: 2.0 Ω ± 0.4 Ω; typically triggers at >2.4 Ω). This passive safety fault in the Supplemental Restraint System (SRS) means the ECU detects a high-resistance condition in the pretensioner circuit. Poor contact, a partial open circuit in the wiring, or an aging internal pretensioner squib can cause this condition. This fault may prevent the second-stage pretensioner from deploying correctly during a collision, reducing occupant restraint protection. The SRS warning light remains illuminated to alert the driver.
B179A-00›
This DTC indicates the Airbag Control Unit (ACU) detects an open or disconnected circuit in the front passenger side second stage seat belt pretensioner. The second stage pretensioner is a critical component of the restraint system. During severe collisions, it works with the first stage, using an igniter to detonate the gas generator and rapidly tighten the seat belt. The ACU continuously monitors this circuit's resistance (normal range: approx. 1.8-3.2Ω). When the ACU detects infinite resistance or a value exceeding the threshold, it determines a disconnected fault and logs B179A-00. This fault prevents the pretensioner from deploying during a collision, reducing chest and head restraint protection for the front passenger. It also illuminates the SRS warning light continuously. Some models may enter a safety protection mode, restricting the normal deployment logic of other airbags.
B179A›
DTC B179A indicates the SRS (Supplemental Restraint System) ECU detects an open circuit or disconnected front passenger-side second-stage seat belt pretensioner. The "second stage" typically refers to the retractor pretensioner (distinct from the first-stage buckle pretensioner), which uses a pyrotechnic igniter to rapidly tighten the seat belt during a collision. The SRS ECU monitors the pretensioner circuit resistance (normally 2.0-4.0 Ω) to determine connection status. The ECU sets this DTC when resistance exceeds the threshold (typically >10 kΩ or a complete open circuit). This fault prevents pretensioner activation during a collision, reducing chest and head restraint protection for the front passenger, and illuminates the instrument panel airbag warning light. Because occupants of various body sizes frequently adjust the front passenger seat, this fault occurs significantly more often in shared vehicles than on the driver side.
B179B-00›
This DTC indicates the front passenger seat belt pretensioner Stage 2 squib circuit is shorted to vehicle power positive (B+). Modern vehicle seat belt pretensioners typically use a dual-stage ignition design: the first stage deploys during the initial collision phase to provide basic restraint, and the second stage deploys upon detecting a more severe collision to increase protective force. A short to power indicates an abnormal high-potential path in the squib circuit, which may cause: 1) The pretensioner to deploy unintentionally in non-collision situations, causing personal injury and property damage; 2) The Airbag Control Unit (ACU) to detect abnormal circuit voltage and enter fail-safe mode, disabling the front passenger airbag and pretensioner functions; 3) Continuous short-circuit current to damage the internal ACU driver circuit or trigger fuse protection. This constitutes a severe electrical fault in the passive safety system and requires immediate repair.
B179B›
DTC B179B indicates a short-to-power fault in the front passenger seat belt pretensioner second-stage deployment circuit. In the BYD SRS (Supplemental Restraint System) architecture, the pretensioner utilizes a dual-stage ignition design: the first stage lightly retracts the seat belt during the initial collision phase, and the second stage forcefully retracts it to secure the occupant as the collision intensifies. This DTC sets when the SRS control module detects an abnormally low-resistance path (typically <1Ω) between the front passenger pretensioner second-stage ignition circuit (usually marked as terminals P+ and P-) and vehicle power (B+) or ground (GND), causing the control module to identify a short circuit. This fault results in the following: 1) the front passenger airbag system enters fail-safe mode, and the instrument cluster airbag warning lamp remains illuminated; 2) the second-stage pretensioner may fail to deploy or deploy unintentionally during an actual collision; 3) because the pretensioner is a pyrotechnic device (containing explosive propellant), continuous short-circuit current creates an accidental ignition and deflagration risk. Therefore, the system classifies the fault as severe (Level 3) and prohibits vehicle operation.
B179C-00›
DTC B179C-00 indicates the Airbag Control Unit (ACU) detects an abnormally low-resistance connection (typically <2Ω) between the front passenger side second-stage seatbelt pretensioner firing circuit and body ground. The second-stage pretensioner is a component of the dual-stage adaptive seatbelt system. During a severe collision, it triggers sequentially with the first stage to provide progressive restraint protection. A short to ground causes the ACU to flag this firing circuit as failed, which illuminates the SRS warning lamp, disables the front passenger side airbag and pretensioner functions, and prevents second-stage pretensioner activation during a collision. This hard fault remains active, and cycling the ignition does not clear it. Repair the wiring insulation or replace the faulty component.
B179C›
DTC B179C indicates an abnormally low-resistance connection between the ignition circuit of the front passenger-side seat belt second stage pretensioner and body ground. In the BYD SRS (Supplemental Restraint System) architecture, a twisted pair typically connects the second stage pretensioner to the Airbag Control Unit (ACU), with a normal resistance of approximately 2.0–3.0 Ω. The ACU sets this DTC when it detects the circuit-to-ground resistance falls below the threshold (typically <1.0 Ω). This fault causes: 1) unintentional pretensioner deployment in non-collision situations, causing personal injury; 2) failure of the pretensioner to deploy correctly during a collision; 3) the ACU to enter fault protection mode, which may subsequently disable the front passenger airbag and side curtain airbags, greatly reducing crash safety. This is a hard fault; once confirmed, it continuously illuminates the SRS warning lamp.
B179E00›
This fault code indicates the Airbag Control Unit (ACU) detects an abnormal electrical series connection between an airbag ignition circuit (e.g., driver/front passenger frontal airbag, side airbag, or curtain airbag) and another vehicle electrical circuit (e.g., another airbag circuit, seat belt pretensioner circuit, or sensor circuit). Normally, each ignition circuit remains independent with a specific resistance (typically 2.0 ± 0.2 Ω). When a series connection occurs, total circuit resistance increases abnormally (combining to exceed 4 Ω) or the control unit detects cross-circuit signal interference. This prompts the ACU to flag compromised circuit integrity. This fault can prevent airbag deployment during a collision (due to insufficient ignition energy) or cause unintended deployment, severely compromising occupant protection.
B179F00›
DTC B179F00 indicates a fault in the sensor series circuit of the SRS (Supplemental Restraint System/airbag system). In the BYD Qin PRO, a series or parallel circuit typically connects multiple safety sensors (including the front impact sensor, side impact sensor, and seat occupancy sensor) to the SRS ECU. The ECU determines sensor status by monitoring the circuit resistance and voltage signals. The ECU triggers this DTC when it detects abnormal circuit resistance (open circuit, short circuit, or resistance outside the calibrated range of 2.0-4.5kΩ), an incorrect signal sequence, or a communication interruption. This fault forces the airbag system into a degraded mode. In extreme cases, it prevents normal airbag deployment during a collision or creates a risk of unintended deployment. This is a safety-critical fault.
B17A000›
DTC B17A000 indicates the airbag control unit (SRS ECU) detected a logic error or hardware fault during its internal self-check. Specifically, this fault indicates a failure in the ECU internal processor, memory (EEPROM/Flash), safety sensor, or power management module. During the power-on self-test, the SRS ECU performs CRC checks and logic diagnostics on the internal accelerometer, crash algorithm logic area, backup power circuit, and CAN communication interface. The ECU sets this code if it detects a data verification failure, RAM test failure, watchdog reset, or internal communication bus fault. This is a functional safety fault that may cause the airbag system to enter fail-safe mode (disabling airbag deployment), fail to provide protection during a collision, or create a risk of unintended deployment.
B17A100›
B17A100 is an internal diagnostic fault code for the BYD SRS (Supplemental Restraint System) control unit. "Invalid Fault" indicates the airbag control module detects data frames from internal logic circuits, external crash sensors, or CAN bus communication containing format errors, CRC check failures, or values outside physically reasonable ranges during self-checks or real-time monitoring. These conditions do not meet other specific fault definitions (such as open circuit, short circuit, or abnormal signal). This fault typically indicates the ECU received "logically implausible" status information. This forces the system into a safety fallback mode (e.g., airbag deactivation, pretensioner standby, or a continuously illuminated fault indicator), severely compromising crash protection functions. In Qin PRO models, this fault commonly stems from ECU internal ADC reference voltage drift, momentary CAN bus interference, or marginal sensor signal values.
B17A200›
This DTC indicates that the airbag control unit (SRS ECU) has detected a collision event meeting the deployment threshold, permanently written the crash data to the ECU internal non-volatile memory (NVRAM), and activated the crash lock protection mechanism. In this state, the SRS system enters safe mode, disables further airbag deployment to prevent secondary injury, and illuminates the warning lamp continuously. A genuine collision event (deployed or recorded without deployment) can trigger this lock. Crash sensor faults, wiring harness short/open circuits, ECU algorithm miscalculations, or power supply system anomalies can also generate a false record. Once locked, standard DTC clearing cannot erase the code. Reset the data using dedicated diagnostic equipment, or replace the ECU.
B17A300›
In the BYD SRS system, DTC B17A300 carries two technical indications: 1) The surface description, "seat belt pretensioner collision", indicates the system detects a trigger signal or ignition circuit fault in the driver or passenger seat belt pretensioner (Pyrotechnic Pretensioner); 2) The underlying technical definition, "SRS CAN Signal Abnormal", means the airbag control unit (ACU) loses communication with the vehicle CAN network (typically the powertrain or comfort network) or detects a data checksum error. This fault forces the airbag system into a degraded mode, potentially preventing airbag and pretensioner deployment during a collision. It also triggers a continuous airbag warning light on the instrument cluster. In models such as the Qin PRO, this fault frequently accompanies B17A200 (collision record locked) or B17A400 (hardwired signal abnormal), indicating the vehicle experienced a collision or the CAN bus physical layer has an intermittent fault.
B17A400›
DTC B17A400 indicates the Supplemental Restraint System (SRS) detects an abnormal signal in the driver-side side airbag circuit or related hardwiring. This DTC typically indicates an open circuit, short circuit, or out-of-range resistance (normal circuit resistance is typically 2.0-5.0Ω) in the hardwired communication between the Airbag Control Unit (ACU) and the driver-side side airbag module (SAB-D), left side impact sensor (SIS), or seat belt pretensioner. This fault can prevent the driver-side side airbag from deploying during an actual collision or trigger the fault warning lamp without a collision, severely compromising passive safety system functionality. The literal fault description reads 'driver side collision'; however, this indicates a side airbag system circuit anomaly, not an actual collision event.
B17A500›
This fault code typically indicates a circuit fault in the left electronic parking brake (EPB) actuator (passenger side). Associated issues include motor damage, abnormal control wiring, or module drive circuit faults. Some documentation labels this code as an SRS 'passenger-side side collision' record. However, field cases on BYD Qin, Han, Song, and Tang models confirm B17A500 indicates an open circuit, short circuit, or current overload in the left EPB motor drive circuit. This fault disables the electronic parking brake (unable to apply or release) and triggers a 'Please check the electronic parking system' instrument cluster warning. Extreme cases cause rear brake drag, increased driving resistance, or parking failure, posing a severe safety hazard.
B17A600›
DTC B17A600 indicates the Airbag Control Unit (ACU) detects a triggered front impact sensor circuit or an abnormal signal. This event-type DTC typically indicates the SRS system recorded a front collision event (regardless of severity), or the Front Impact Sensor (FIS) and its wiring harness have an electrical fault (such as a short circuit, open circuit, or abnormal impedance). On BYD Qin PRO models, the front impact sensors typically mount on both sides of the front longitudinal rails or radiator support frame to detect front-end acceleration changes. The ACU sets this code when it detects a sensor signal exceeding the threshold (>2.5g for a specific duration) or abnormal sensor circuit resistance (normally approx. 2.0-3.0kΩ). This fault may prevent airbag deployment or cause accidental deployment. Repair the vehicle immediately.
B17A700›
This DTC indicates the Airbag Control Unit (ACU) recorded a rear collision event. The system sets this code when the Rear Impact Sensor detects a deceleration threshold trigger in a specific direction, or the accelerometer integrated within the SRS control unit identifies a G-value change consistent with a rear collision. This event-recording DTC may accompany seat belt pretensioner activation or an airbag deployment command. Upon storing this code, the system illuminates the airbag fault warning lamp, may disable specific airbag functions to prevent unintended secondary deployment, and records key collision data in the freeze frame (such as vehicle speed, seat occupancy status, and seat belt buckle switch status) for accident analysis. If no actual collision occurred, the sensor or control unit has an electrical fault or signal interference.
B17FF-00›
DTC B17FF-00 indicates the airbag control unit (SRS ECU) continuously detects an abnormal vehicle speed pulse signal input or completely loses the vehicle speed signal. In BYD Qin series vehicles, the SRS system receives the vehicle speed pulse signal from the wheel speed sensors (ABS sensors) or the vehicle control unit (VCU) via hardwire or the CAN bus. The crash judgment algorithm uses this signal—the system determines the airbag deployment trigger threshold, ignition timing, and multi-stage airbag deployment intensity based on real-time vehicle speed. The SRS ECU stores this DTC when it detects, within a set time window (typically exceeding 2-5 seconds), that the pulse signal frequency falls outside the valid range (such as the frequency corresponding to 0-255 km/h), the signal completely drops out, or the signal deviates significantly from the vehicle speed data transmitted on the CAN bus. This fault forces the airbag system into Degradation Mode. During a collision, the airbags may deploy late, fail to deploy, or deploy inadvertently at low speeds, severely compromising passive safety performance.
B17A800›
The BYD SRS (airbag system) control unit logs diagnostic trouble code (DTC) B17A800 to indicate interrupted communication or a physical layer connection fault between the airbag control module and the vehicle CAN bus network. In models such as the BYD Qin PRO, the SRS ECU exchanges real-time data with the vehicle control unit (VCU), body control module (BCM), instrument cluster, and gateway via the CAN bus (typically the powertrain CAN or chassis CAN, depending on the configuration). The ECU transmits critical safety data, including crash signals, airbag status, fault information, and system readiness status. The SRS ECU sets this fault code when it continuously detects abnormal voltage on the CAN_H and CAN_L lines (recessive level outside the normal 2.0-3.0 V range, or abnormal dominant level), bus termination resistance deviating from the standard 60 Ω value (after parallel connection), or no valid data frame received within the specified time limit (usually 250 ms-500 ms). This functional safety fault may prevent proper airbag deployment and seat belt pretensioner operation during a collision. It also disables the collision-triggered automatic unlocking and high-voltage cut-off functions. As a result, the instrument panel airbag warning lamp remains illuminated and the vehicle enters safety protection mode.
B17FF›
DTC B17FF indicates an abnormal vehicle speed pulse signal at the airbag control unit (SRS ECU). In BYD electronic architecture, wheel speed sensors typically generate the vehicle speed signal. The ABS/ESP control unit processes this signal and transmits it via the CAN bus to the instrument cluster and SRS module. The SRS system relies on accurate vehicle speed data for crash algorithm decisions: low-speed collisions (<25km/h) normally do not trigger the front airbags, while medium- and high-speed collisions require precise vehicle speed data to calculate airbag deployment timing and ignition level. When the SRS module detects the vehicle speed pulse signal is missing, out of range, erratic, or inconsistent with CAN bus vehicle speed data, it logs DTC B17FF and illuminates the airbag warning light. The system enters a degraded mode, potentially causing unintended or delayed airbag deployment during a collision.
B185014›
This fault code indicates a short to ground or open circuit in the rear HVAC blower motor speed control signal circuit. Modern BYD vehicles typically use a PWM (pulse-width modulation) signal or an analog voltage signal (0-5V/0-12V) for stepless rear blower speed control. The HVAC ECU triggers this fault code when it detects an abnormal control signal voltage (a constant 0V short to ground or a high-impedance open circuit) to the rear blower speed control module (power transistor) or blower motor. This fault results in no airflow from the rear HVAC vents, prevents fan speed adjustment, or restricts operation to a fixed fan speed. In extreme cases, it triggers the HVAC thermal management protection and limits battery or motor cooling capacity, classifying this as a severe fault.
B2A0716›
The internal voltage monitoring circuit in the Air Conditioning Control Unit (ACU) or Integrated Thermal Management System (ITMS) controller triggers DTC B2A0716. This indicates the supply voltage in power circuit 161 (typically the constant B+ or IG ignition supply for the air conditioning module) falls below the 9V operating threshold. This fault signifies a low-voltage supply abnormality in the thermal management system. Upon detecting insufficient operating voltage, the controller logs the fault and may enter a degraded protection mode. This mode limits the electric compressor speed, shuts off the PTC heater, or halts electronic expansion valve operation, reducing or disabling air conditioning cooling and heating functions. In extreme cases, this condition affects the traction battery cooling circuit and triggers overheat protection.
B2A0717›
This DTC indicates the A/C controller or thermal management system control module detects a power supply voltage exceeding the 16V safety threshold. In BYD new energy vehicles, the DC-DC converter typically converts high-voltage traction battery energy to power the low-voltage system (12V/14V system). Normal output voltage should range between 13.5V and 14.5V. When the monitoring point voltage continuously exceeds 16V, the controller identifies an overvoltage condition and triggers a protection mechanism to prevent electronic component damage. This fault may restrict A/C system functions, reduce thermal management efficiency, or force the system into a power derating mode. Extreme cases may damage sensitive electronic components on the control board. The '161' in the DTC typically refers to a specific voltage monitoring circuit or sensor number.
B2A0811›
On BYD new energy vehicles, DTC B2A0811 indicates a short to ground or abnormal signal transmission in the Electric A/C Compressor control circuit. Although the original description mentions a 'PT temperature sensor', repair practice links this code primarily to unintended continuity between the Compressor Controller low-voltage control circuit (12V supply, PWM signal, or CAN communication line) and body ground, or a breakdown short circuit of the internal power transistor (IGBT). This fault forces the compressor controller into protection mode and stops high-voltage output, causing complete air conditioning failure or intermittent system shutdown. Because new energy vehicles rely on the air conditioning system for battery thermal management, this fault can cause insufficient traction battery cooling, trigger overheat protection, and limit vehicle power. This serious fault compromises driving safety.
B2A0813›
DTC B2A0813 indicates an open circuit in the air conditioning system evaporator outlet refrigerant temperature sensor (PT sensor) circuit. This sensor uses an NTC thermistor to monitor the evaporator outlet refrigerant temperature in real time (typical range -40°C to +85°C). It provides critical temperature feedback to the HVAC ECU to precisely control the electronic expansion valve opening, compressor speed, and blower airflow, preventing evaporator surface icing and optimizing cooling efficiency. The ECU logs an open circuit fault when it detects the sensor signal voltage continuously exceeding the threshold (typically above 4.95V, indicating an open circuit) for longer than a set time (e.g., 2 seconds). This fault triggers the air conditioning system fail-safe mode, forcibly limiting compressor operation or completely stopping cooling, and may illuminate the relevant thermal management warning lamp. Continuing to drive the vehicle may cause abnormal battery pack or motor heat dissipation, making this a severe fault.
B2A0D13›
DTC B2A0D13 indicates an open circuit in the Battery Pack Inlet Coolant Temperature Sensor. This sensor is located at the inlet of the battery thermal management system cooling circuit. Typically an NTC thermistor, the sensor provides a 0-5V analog voltage signal to the Battery Management System (BMS) or Thermal Management Controller (TMS) to monitor the temperature of the coolant entering the battery pack in real time. An open circuit fault means the control unit detects that the signal voltage remains continuously in an open-circuit state (typically the 5V reference voltage or 0V, depending on circuit design), preventing it from obtaining actual temperature data. This fault causes the thermal management system to enter fail-safe mode. The system cannot accurately regulate the battery pack temperature, which may result in the following: (1) The system disables high-power charging and discharging, limiting vehicle power output. (2) The battery coolant pump and PTC heater fail to regulate to the target temperature, creating a risk of battery overheating or low-temperature damage. (3) In extreme cases, the system triggers the high-voltage interlock, preventing the vehicle from starting.
B2A0E12›
This DTC indicates a short to battery in the signal circuit of the Battery Thermal Management System (BTMS) inlet coolant temperature sensor (typically located on the line before the battery cooling circuit enters the battery pack). The sensor utilizes an NTC (Negative Temperature Coefficient) thermistor and outputs a 0-5V analog voltage signal to the BMS or thermal management controller during normal operation. During a short to battery (12V), the ECU detects a continuous signal voltage above the normal range (e.g., >4.8V or equal to battery voltage) and registers a short circuit fault. This fault prevents the BMS from accurately reading the battery pack inlet coolant temperature, affecting the battery thermal management strategy and potentially triggering: 1) Disabled battery fast charging or limited discharge power; 2) False battery over-temperature protection triggers, forcing the battery cooling system (electric compressor, water pump) to operate; 3) Thermal runaway risk in extreme cases due to the inability to monitor actual battery temperature. This is a severe DTC. Inspect and repair immediately due to the high-voltage battery system thermal runaway risk.
B2A0F13›
This fault code indicates an open circuit in the refrigerant temperature sensor signal circuit at the inlet or outlet of the plate heat exchanger (chiller, battery cooler). The sensor is an NTC thermistor that monitors the temperature of the refrigerant exchanging heat with the battery coolant, serving as a key feedback component in the BYD thermal management system. The ECU monitors this temperature to adjust the electronic expansion valve opening and electric compressor speed, precisely controlling the battery pack temperature. When the ECU detects the sensor signal voltage continuously exceeding the upper threshold (typically the 5V reference voltage, indicating an open circuit), it sets an open circuit fault. The thermal management system consequently loses precise control over battery cooling and heating. This failure may trigger the battery thermal management protection strategy, forcing the vehicle into power limitation mode (limp mode), disabling fast charging, or triggering a high coolant temperature warning. Extreme cases pose a risk of battery thermal runaway.
B2A1012›
This DTC indicates a short to ground in the refrigerant temperature sensor signal circuit at the inlet or outlet of the battery cooling system plate heat exchanger (Chiller/battery cooler), or an internal short circuit within the sensor. This NTC thermistor outputs a 0.5-4.5 V analog voltage signal to the Thermal Management System (TMS) controller or A/C controller to monitor the temperature of the refrigerant flowing through the plate heat exchanger in real time. This parameter is critical for precisely controlling battery cooling intensity and preventing battery overcooling or overheating. The controller logs a short circuit fault when the signal voltage remains below 0.1 V (near 0 V) for a specified duration (typically 2-5 seconds). The thermal management system then enters fail-safe mode, immediately cutting off refrigerant flow to the battery cooling circuit and limiting battery charge and discharge power. In severe cases, the system triggers a vehicle-level 'Thermal Management System Fault' warning and prohibits high-voltage power-on. This prevents continued operation with unknown refrigerant temperatures, which could cause battery thermal runaway or compressor liquid slugging damage.
B2A1113›
This DTC indicates an open circuit in the refrigerant pressure sensor signal circuit at the plate heat exchanger (Chiller/battery cooler) of the thermal management system. The sensor monitors the refrigerant pressure flowing through the plate heat exchanger and serves as a key feedback component for the battery thermal management and cabin air conditioning systems. An open circuit causes the ECU to receive an open-circuit voltage (typically the saturated 5V reference voltage or 0V), preventing it from acquiring actual pressure data. This forces the thermal management control unit to enter fail-safe mode, which limits battery fast-charging power, disables the battery cooling function, and reduces drive motor power. In extreme cases, this fault triggers a battery high-temperature warning or shuts down the high-voltage system, severely impacting vehicle safety and driving range.
B2A1212›
This DTC indicates the Thermal Management Control Unit (TMS) or air conditioning control module detects a short circuit in the signal circuit of the high-pressure side pressure sensor for the plate heat exchanger (Chiller/battery cooler) refrigerant circuit. The sensor outputs an abnormal voltage (near 0 V when shorted to ground, or near 5 V or 12 V when shorted to power), exceeding the normal 0.5–4.5 V signal range. This piezoresistive sensor monitors real-time refrigerant circuit pressure (typically 0–3.5 MPa) to control the Electronic Expansion Valve (EXV) opening and regulate compressor speed. The short circuit eliminates system pressure feedback and prevents accurate refrigerant flow control. This fault can trigger thermal management derating: limiting battery fast-charging power, prohibiting high-power discharge, and reducing motor power output. In extreme cases, the loss of overpressure protection can cause pipe rupture or compressor damage.
B2A2013›
BYD technical documentation defines DTC B2A2013 as "Evaporator Temperature Sensor Circuit Open," rather than a generic "cabin temperature sensor" fault. Located inside the HVAC evaporator case, this sensor monitors the evaporator core surface temperature in real time. It sends critical feedback to the air conditioning controller (AC ECU) to prevent evaporator icing, regulate compressor displacement, and control the electronic expansion valve opening. The AC ECU logs an open circuit fault when it detects the sensor signal voltage remaining above 4.95V or below 0.05V (outside the valid range). This fault triggers the A/C system protection logic, which forcibly disengages the compressor electromagnetic clutch or stops the electric compressor, completely disabling A/C cooling. Because BYD New Energy Vehicles (NEVs) deeply integrate the A/C and battery thermal management systems (typically incorporating the battery chiller into the A/C refrigerant circuit), this fault can cascade into a battery cooling system failure. This causes abnormal vehicle thermal management and may restrict power output.
B2A2111›
In-Car Temperature Sensor signal circuit short to ground. This sensor typically mounts near the center instrument panel air vent or inside the HVAC duct and uses a Negative Temperature Coefficient (NTC) thermistor. Normal operating voltage ranges from 0.5-4.5V (varying with temperature). When the HVAC ECU detects the sensor signal line voltage remaining below 0.5V for longer than the set time threshold (typically 2-5 seconds), it determines a short to ground. This fault causes the air conditioning system to lose the cabin ambient temperature feedback signal, resulting in automatic temperature control failure, disrupted compressor start-stop logic, and abnormal outlet air temperature (continuous maximum cooling or heating). The fault may also affect the battery thermal management system comfort control strategy and, in severe cases, trigger Level 3 fault protection to limit air conditioning power.
B2A2311›
DTC B2A2311 indicates a short to ground or short to power in the Ambient Temperature Sensor (ATS) signal circuit. This causes the air conditioning controller (ACECU) or thermal management controller (TMCU) to detect a voltage signal outside the normal range (typically 0.1-4.9V). The sensor is an NTC thermistor with a normal resistance of approximately 2.3-2.5 kΩ at 25°C. A short circuit causes the ECU to continuously receive an abnormally high or low temperature signal (depending on the short type). This triggers automatic air conditioning system protection, prevents compressor startup, limits PTC heater power, and affects the battery thermal management system cooling or heating strategy. Extreme cases may trigger high-voltage interlock protection and limit overall vehicle power output.
B2A2213›
DTC B2A2213 indicates an open circuit fault in the Ambient Temperature Sensor circuit. Typically an NTC (Negative Temperature Coefficient) thermistor installed near the front bumper or side mirror, this sensor monitors ambient temperature in real time and sends a feedback signal to the HVAC ECU. The controller logs an open circuit if it detects the sensor signal voltage remaining continuously high (typically the undivided 5V reference voltage, representing an open circuit) beyond the set threshold (generally 2–5 seconds). This fault prevents the automatic air conditioning system from accurately calculating the target outlet air temperature. It affects compressor start-stop control, PTC heater power regulation, fresh/recirculated air switching logic, and battery thermal management strategies (such as low-temperature charging preheating and high-temperature cooling activation). In extreme cases, the system triggers thermal management derating protection and limits motor power output to protect the high-voltage powertrain. Therefore, the system classifies this as a severe fault.
B2A2413›
DTC B2A2413 indicates the air conditioning control unit (AC ECU) detects an open circuit in the evaporator temperature sensor circuit. This sensor, typically a negative temperature coefficient (NTC) thermistor, mounts to the evaporator fin surface inside the HVAC assembly. It monitors real-time evaporator core temperature (normal operating range: 2–8°C). If the sensor fails open, the wiring harness disconnects, or the connector has poor contact, the ECU detects a continuous 5V signal (or open-circuit voltage) and cannot obtain accurate evaporator temperature data. The system then triggers a protection strategy. To prevent evaporator icing, expansion, and core damage, the ECU forcibly disengages the compressor electromagnetic clutch or disables the electric compressor. It may also default to a substitute value (such as 0°C or ambient temperature) to maintain limited cooling. This causes air conditioning performance to degrade severely or fail completely. Prolonged operation with this fault can cause frequent compressor cycling, abnormal battery pack thermal management (on models where the air conditioning system couples with battery cooling), and even high-voltage system insulation faults.
B2A2511›
DTC B2A2511 indicates a circuit fault in the left front seat belt pretensioner (Driver Seat Belt Pretensioner), specifically a short to ground or an open circuit. The Airbag Control Module (ACM) sets this fault code when it detects abnormal resistance in the left front pretensioner circuit (standard value: 2-3 Ω; fault condition: short circuit at <1.0 Ω, or open circuit at >4.0 Ω/infinite resistance). This fault forces the airbag system into fail-safe mode and continuously illuminates the instrument cluster airbag warning light. In a collision, the pretensioner may fail to deploy. This severe fault compromises driving safety. Note: Some online sources incorrectly identify this code as the evaporator temperature sensor; it strictly applies to the seat belt pretensioner system.
B2A2712›
This DTC indicates the signal circuit of the automatic air conditioning system’s sun sensor (solar intensity sensor) has shorted to the vehicle power supply (B+, usually a constant 12V supply). The sun sensor generally uses a photodiode or photoresistor. During normal operation, the sensor outputs an analog voltage signal of 0.1-4.9V to the air conditioning controller (integrated into the thermal management module). The signal voltage increases as sunlight intensity increases. When the signal wire shorts to power, the controller detects the voltage remains continuously above 4.9V (close to battery voltage, 12-14V) and logs a short-to-power fault. This fault disables the automatic air conditioning system's solar compensation function. The air conditioning controller cannot automatically adjust outlet air temperature and blower speed based on sunlight intensity. In extreme cases, the short-circuit current may burn out the air conditioning controller's internal sampling circuit. Consequently, the system reports a severe fault and may enter protection mode.
B2A2912›
This fault code indicates abnormal continuity between the air conditioning system defrost flap actuator (Mode Actuator/Defrost Motor) drive circuit and the vehicle positive power supply (12V/B+). In BYD new energy vehicles, the defrost motor is a stepper motor or DC servo motor that drives the mode flap inside the HVAC housing to switch between face, foot, defrost, and other air distribution modes. When the air conditioning control module (ACU) or body control module (BCM) detects a short to power in this motor control circuit, it triggers DTC B2A2912 and enters protection mode. The module stops drive output to the motor to prevent control chip burnout or wiring harness fires. This fault disables the front windshield defrost function, severely compromising driving visibility and safety in low-temperature or high-humidity environments. Secondary risks include blown air conditioning system fuses or control module overheating.
B2A2914›
DTC B2A2914 indicates a short to ground or open circuit in the HVAC Defrost Door Actuator drive circuit. The air conditioning control module (ACECU) controls this actuator via a PWM signal or LIN bus to switch the door to the front windshield defrost mode. The "14" in the fault code indicates the ECU detects abnormal circuit current: excessive current (short to ground) or zero/extremely low current (open circuit). This fault disables the front windshield defrost function, causing glass fogging in low-temperature, high-humidity environments and severely impairing driving visibility and safety. Additionally, due to the integrated logic between the thermal management and air conditioning systems, this fault may trigger a thermal management safety protection strategy, limit air conditioning compressor power, or illuminate the relevant high-temperature warning light.
B2A2992›
This DTC indicates the HVAC Defrost Mode Actuator fails to reach the control module's commanded target position within the specified time. The defrost motor, typically a stepper motor or DC gear motor with position feedback (potentiometer or Hall sensor), drives the mode door to engage the front windshield defrost mode. After sending a position command, the HVAC control module continuously monitors the position sensor feedback voltage (typically a 0-5V analog signal or PWM signal). The module triggers DTC B2A2992 if the deviation between the actual and target positions exceeds the threshold (e.g., 5%-10%) within the specified time (typically 10 seconds), or if it detects abnormal motor current (stall current). This fault disables the defrost function or causes abnormal airflow distribution. In low-temperature and high-humidity environments, the system fails to defog the front windshield, severely compromising driving safety.
B2A2A12›
DTC B2A2A12 indicates a short to vehicle power positive (B+) in the HVAC mode door actuator motor or its control circuit. This stepper or DC geared motor drives the mode door to switch between face, foot, and defrost modes. The A/C ECU logs a short to power when it detects the motor drive circuit current abnormally exceeding the threshold (typically >2A) or the feedback voltage remaining continuously high. This fault causes: 1) the air outlet mode to lock in the default position (typically defrost or face mode) and prevents adjustment; 2) the controller’s internal driver chip to trigger overheat protection, potentially blowing a fuse; 3) a risk of circuit overheating in extreme cases. Because this fault impairs the front windshield defrost function, it carries a severe classification and requires immediate repair.
B2A2A14›
DTC B2A2A14 indicates a short to ground or open circuit in the A/C system mode door actuator (Mode Motor) control circuit. The mode motor is the core actuator in the HVAC door system, switching the door between FACE, FOOT, DEF, and other positions. This fault indicates the integrated Body Control Module (BCM) detects abnormal circuit current (high current indicates a short circuit; low current indicates an open circuit) or a lost position feedback signal when driving the mode motor. Consequently, the BCM cannot accurately control the door position. This fault locks the A/C outlet mode in a fixed position or causes complete failure, severely impacting driving comfort and safety (especially if the front windshield defogging function fails). This fault usually appears alongside DTC B2A2A92 (mode motor fails to reach position). As a hard-wired circuit fault, it requires immediate repair to prevent further damage to the BCM drive circuit.
B2A2A92›
DTC B2A2A92 indicates the Mode Door actuator in the HVAC assembly cannot reach the target position commanded by the control module, or the actual position reported by the position sensor deviates from the target position by more than the allowed threshold (typically ±5°). This fault involves the A/C airflow direction control mechanism. The mode motor drives the mode door flap to switch airflow direction between face, foot, and defrost modes. The integrated Body Control Module (BCM) sets this fault code if it does not receive the correct position signal from the position sensor within the specified time after sending an adjustment command, or if it detects a motor stall or abnormal current. This fault causes the airflow mode to become fixed or unresponsive, reducing occupant comfort. It may also indirectly affect thermal management system efficiency (e.g., defrost function failure compromising safety).
B2A2B12›
DTC B2A2B12 indicates a short to vehicle power positive (B+) in the driver-side HVAC blend door actuator control circuit. The motor receives commands from the HVAC controller via LIN bus or PWM signal, drives the gear mechanism to adjust the hot/cold air mix ratio, and provides position feedback through a potentiometer or Hall sensor. A short to power typically results from insulation failure between the motor power supply line (usually constant 12V) and the signal or ground line, or an inter-turn breakdown in the motor internal winding causing abnormally low impedance. This fault causes the HVAC controller to detect abnormally high voltage (near battery voltage), trigger circuit protection, and cut off the circuit output. This prevents driver-side vent temperature adjustment (stuck in hot or cold position). Severe cases can burn out the HVAC controller internal driver chip or blow a fuse, affecting normal vehicle thermal management system operation.
B2A2B14›
DTC B2A2B14 indicates an electrical fault in the driver-side A/C blend door actuator. This stepper or DC motor actuator drives the hot/cold blend door inside the HVAC unit to adjust the driver-side outlet temperature. A "short to ground" occurs when the motor power supply circuit (B+) or control circuit abnormally connects to the vehicle body ground (GND), typically due to damaged insulation or burnt motor windings. This condition can blow the fuse or trigger a protective shutdown of the A/C controller. An "open circuit" indicates interrupted electrical continuity in the motor circuit, likely caused by a burnt coil, broken wiring harness, or loose connector. This fault disables driver-side temperature adjustment, locking the door in the hottest or coldest position. Driving with an active short circuit risks wiring overheating or fire, classifying this as a severe fault.
B2A2B92›
This fault code indicates the driver-side HVAC (Heating, Ventilation, and Air Conditioning) temperature blend door actuator (hot/cold blend door motor) cannot reach the target position or the position feedback signal is abnormal. The actuator uses a stepper motor or DC motor to drive a gear mechanism, adjusting the hot/cold blend door opening (0-100%). This accurately controls the airflow mixing ratio through the heater core and evaporator, providing stepless adjustment of the outlet air temperature. The air conditioning controller (AC ECU) logs this fault code if the deviation between the actual and target positions continuously exceeds the calibrated threshold (typically 5-10%) or if the motor stall current times out. Triggering conditions include a faulty motor drive circuit, position sensor (potentiometer) signal drift, a binding gear drive mechanism, or excessive mechanical resistance at the blend door shaft. This fault causes driver-side temperature adjustment failure, abnormal outlet air temperature (stuck excessively cold or hot), unstable temperature control in automatic air conditioning mode, or a clicking gear noise during temperature adjustment.
B2A2C12›
DTC B2A2C12 indicates a short to battery positive (B+) in the drive circuit of the passenger-side temperature control flap actuator (air mix motor/blend door actuator). In the BYD thermal management system, the air mix motor controls the hot and cold air mixing ratio via a PWM signal to adjust the passenger air outlet temperature. A short to power means the resistance between the motor power supply or control line and the battery positive terminal drops abnormally (typically <1Ω). This causes the HVAC ECU to detect an abnormal voltage (near 12V battery voltage instead of the normal 0-5V PWM signal or feedback voltage), triggering the overvoltage protection mechanism and stopping the motor drive. This fault prevents passenger-side temperature adjustment, typically leaving the flap stuck in a fixed position or defaulting to maximum hot or cold. Extreme cases risk wiring overheating, blown fuses, control module damage, or localized overheating.
B2A2C14›
DTC B2A2C14 indicates a drive circuit fault in the front passenger side temperature blend door actuator (hot/cold motor), specifically a short to ground (abnormal connection to vehicle ground causing overcurrent) or an open circuit (circuit interruption, infinite resistance). The integrated Body Control Module (BCM) controls this motor via a PWM signal or stepper drive to adjust the front passenger side hot/cold air mixing ratio, enabling dual-zone climate control. The BCM sets this DTC upon detecting abnormal motor drive current (excessive or zero), an abnormal position feedback signal, or a LIN communication fault. This fault prevents front passenger side temperature adjustment (sticking in the cold or hot position). In severe cases, the BCM may enter protection mode, limiting overall air conditioning system functionality and potentially affecting the thermal management system's control of battery or motor temperatures.
B2A2C92›
This DTC indicates the front passenger side temperature flap actuator (air mix flap motor) cannot reach the target position or the position feedback signal is abnormal. The integrated Body Control Module (BCM) drives this stepper/DC motor via the LIN bus or PWM signal to adjust the air mix flap opening and control the front passenger outlet temperature. "Cannot reach position" means the motor fails to reach the target angle within the set time (typically 3-5 seconds), or the position sensor feedback voltage deviates from the expected value by more than the threshold (generally >5%). This fault disables front passenger temperature adjustment (no hot or cold air). Severe cases may cause abnormal flap noise or trigger air conditioning system protection mode, but typically do not affect vehicle driving safety.
B2A2F09›
DTC B2A2F09 indicates the air conditioning thermal management system detected abnormal refrigerant line pressure. Specifically, the high-pressure side pressure sensor reading falls outside the normal range (too high or too low). This fault involves the electric compressor high-pressure line monitoring circuit. The system triggers the fault when the pressure sensor detects a high-pressure side pressure > 3.2 MPa (overpressure protection) or < 0.2 MPa (underpressure protection). This fault activates the air conditioning system safety protection mechanism and forces an electric compressor shutdown to prevent pipe rupture or compressor dry running, resulting in a loss of cooling. In BYD new energy vehicles with highly integrated thermal management systems, this fault may also impair the battery cooling function, triggering vehicle thermal management power derating protection.
B2A3214›
This DTC indicates the air conditioning control unit (ACU) or thermal management controller detects an abnormal electrical condition in the front HVAC blower motor power supply circuit, specifically a short to body ground (impedance <1Ω) or an open circuit/high resistance (impedance >10kΩ). In the BYD e-platform architecture, a PWM (pulse-width modulation) or LIN bus communication speed control module typically controls the blower motor. The ACU determines the circuit status by monitoring the blower motor current or feedback signal. The ACU triggers this DTC when it detects sustained high current (short circuit) or zero current (open circuit) exceeding the calibrated threshold (typically 200ms-1s). This fault prevents the front HVAC module from supplying air and affects cabin temperature regulation. In extreme cases, a short circuit can overheat the wiring harness and trigger the high-voltage interlock protection.
B2A3314›
DTC B2A3314 indicates a short to ground or open circuit in the Front Left Corner Sensor signal circuit. This fault code belongs to the Park Assist System (APA) / Around View Monitor (AVM) system, not the thermal management system. The APA control module sets this fault when it detects the Front Left Corner Sensor signal voltage remains below 0.5V (short to ground) or above 4.5V (open circuit) for more than 500ms. This fault causes front left obstacle detection failure, potentially triggering false park assist warnings or complete loss of function. The system classifies this as a severe fault because it may affect Automatic Emergency Braking (AEB) operation in extreme cases.
B2A4B12›
DTC B2A4B12 indicates a short to power in the HVAC circulation air door actuator drive circuit. When driving the circulation motor (typically a 12V DC permanent magnet or stepper motor), the AC ECU detects an abnormally low-resistance path between the motor drive circuit (M+ or M- terminal) and the vehicle power supply (B+), causing an abnormal current increase. This hard short circuit triggers the controller's overcurrent protection. Severe cases may cause: 1) the air door to stick in the recirculation or fresh-air position, failing to switch based on operating conditions; 2) the motor to stall and overheat, reducing thermal management efficiency; 3) reverse short-circuit current to damage the AC ECU power drive module; 4) a fire risk due to continuous circuit heating in extreme conditions. This fault and B2A4B14 (short to ground/open circuit) form a mutually exclusive diagnostic pair that jointly monitors the circulation motor circuit integrity.
B2A4B14›
This DTC indicates a fault in the drive circuit of the HVAC Recirculation Air Door Actuator motor. Specifically, a "short to ground" indicates insulation failure between the motor supply line (typically the PWM control line or power line) and the vehicle body ground (GND), causing abnormal current leakage. An "open circuit" indicates a broken internal motor coil, a loose connector, or a severed wiring harness. This motor switches the HVAC air door between fresh air and recirculation modes. A fault prevents mode switching or causes the door to stick in a fixed position, reducing cabin temperature control efficiency. In extreme cases, this reduces battery thermal management performance (e.g., preventing effective heat dissipation via fresh air mode). Therefore, the system classifies this as a severe fault.
B2A4B92›
This fault code indicates abnormal damper actuator position control within the air conditioning thermal management system. Specifically, the recirculation door or blend door servo motor fails to reach the target position within the set time (typically 3-5 seconds), or the actual position feedback from the position sensor (generally a Hall effect sensor) deviates from the controller command by more than the threshold (typically >5%). According to the control logic, the AC controller outputs a PWM signal to drive the motor while monitoring the sensor feedback voltage (0.5-4.5V range). The controller triggers this code upon detecting a motor stall, step loss, sensor signal interruption, or abnormal voltage. This fault disables fresh air/recirculation switching, delays cabin temperature adjustment, and causes abnormal demist mode operation. In extreme cases, it affects battery pack cooling efficiency on vehicles utilizing an A/C refrigerant battery cooling architecture.
B2A4E13›
DTC B2A4E13 indicates an open control circuit fault in the left front (driver side) seat belt pretensioner. It belongs to the body safety system (SRS), not the thermal management system. DTC structure breakdown: 'B' represents the Body system, '2A4E' designates the left front seat belt pretensioner control circuit, and '13' indicates an open circuit. The Airbag Control Unit (ACU) triggers this fault upon detecting abnormal resistance (open circuit or excessive resistance) in the pretensioner circuit, which prevents the formation of an effective monitoring circuit. This fault continuously illuminates the instrument cluster SRS warning light and forces the airbag system into a degraded mode. In extreme cases, it prevents the pretensioner from deploying during a collision, posing a severe safety risk. Note: Unofficial sources sometimes incorrectly label this code as a high-voltage line pressure sensor fault; it strictly indicates a seat belt pretensioner circuit fault.
B2A4F11›
DTC B2A4F11 indicates a short to battery in the signal circuit of the air conditioning system high-pressure line pressure sensor. In BYD new energy vehicle thermal management systems, a 5V reference voltage typically powers this sensor. The sensor outputs a 0.5–4.5V analog voltage signal reflecting the refrigerant high-side pressure (normal range approximately 0.8–2.8V, corresponding to 0.3–3.0MPa). The ECU logs a short to battery when it detects the sensor signal voltage remaining above 4.8V or near the reference supply voltage (5V) for longer than the calibrated time (typically over 200ms). This fault prevents the air conditioning ECU from accurately reading high-side pressure data and triggers system protection strategies: disabling the electric compressor and suspending cooling/heating functions. In severe cases, the system may limit vehicle power output to prevent loss of thermal management control. The short circuit can occur within the sensor, the wiring harness connector, or the internal ECU sampling circuit.
B2A5112›
DTC B2A5112 indicates a short circuit in the thermal management system Pressure Transducer (PT). Specifically, the signal circuit shorts to power or ground (BYD DTC subtype definition '12' typically indicates a short to power). This sensor mounts in the air conditioning high-pressure line or battery coolant circuit. It monitors refrigerant or cooling system pressure in real time, providing key parameters to the thermal management controller (TMS) or air conditioning controller to regulate electric compressor speed, electronic expansion valve opening, and cooling fan speed. During a short circuit, the controller loses accurate pressure readings and enters fail-safe mode. This can disable the air conditioning, reduce battery cooling, and trigger motor over-temperature protection. In severe cases, the system limits drive power or disables driving to prevent critical component damage from thermal management failure.
B2A5811›
This DTC indicates a short to ground in the driver-side face vent (FACE mode) temperature sensor signal circuit. The sensor is an NTC (negative temperature coefficient) thermistor. During normal operation, it sends a 0.5-4.5V analog voltage signal to the air conditioning control unit (ACU) to indicate the vent outlet temperature. When the ACU detects the signal voltage remains below 0.1V (logic low threshold) for longer than the set time (typically 200-500ms), it determines a short to ground. This fault causes the ACU to enter Limp Home Mode, disables independent dual-zone temperature control, and may lock the driver-side temperature flap in the full cold or full hot position, severely affecting air conditioning comfort. In extreme cases, continuous full-load compressor operation affects overall vehicle energy consumption.
B2A5C14›
DTC B2A5C14 indicates a short to ground or open circuit in the Heater Core Three-Way Water Valve drive motor circuit. The three-way water valve acts as a key thermal management system actuator. It controls the flow path of engine coolant or PTC heating fluid to the heater core to distribute flow for cabin heating and battery thermal management. Damaged wiring insulation contacting the vehicle body typically causes a short to ground; the resulting excessive current can burn out the drive circuit. Broken wiring, a loose connector, or a burnt-out internal motor winding can cause an open circuit. This fault completely disables the heating function and forces the thermal management system into Limp Home mode. In extreme cases, it compromises battery temperature regulation. Consequently, the system classifies this as a Level 3 (severe) fault and triggers a protection mechanism. This restricts continued vehicle use to prevent circuit overheating or further damage.
B2A5911›
This DTC indicates a short to chassis ground (GND) in the signal circuit of the driver-side Foot Outlet Temperature Sensor. In the BYD thermal management system, this NTC thermistor sensor monitors the actual temperature at the foot air duct outlet. The signal voltage is typically a 0-5V analog signal. A short to ground causes the ECU to continuously read an abnormally low voltage near 0V, registering a corresponding temperature of -40℃ or an extreme low. This forces the air conditioning control unit into fault protection mode. The system may force the compressor off, switch to demist mode, or restrict battery coolant flow. These conditions severely impact occupant comfort and battery/motor thermal management efficiency. In extreme cases, this triggers high-voltage system overheat protection.
B2A5913›
This DTC indicates an open circuit in the signal circuit of the driver-side footwell air outlet temperature sensor (NTC negative temperature coefficient thermistor). In BYD dual-zone/multi-zone automatic air conditioning systems, this sensor provides real-time footwell air outlet temperature feedback to the air conditioning controller (integrated into the right domain controller) for closed-loop temperature control. An internal open circuit in the sensor, an open circuit in the wiring harness, or poor connector contact causes the controller to detect a signal voltage outside the valid range (typically reading -40°C or a fixed high voltage) and trigger this DTC. This fault disables driver-side temperature control and may force the compressor into protection mode. In extreme cases, it disrupts the coordinated operation of the battery thermal management system (on models with coupled air conditioning and battery cooling circuits).
B2A5A11›
This DTC indicates a short to ground in the signal circuit of the front passenger side FACE mode outlet air temperature sensor. In the BYD dual-zone automatic air conditioning system, this sensor uses an NTC (negative temperature coefficient) thermistor. Under normal conditions, sensor resistance decreases as temperature increases (approximately 2 kΩ at 20°C). The air conditioning controller calculates the actual outlet air temperature by detecting the voltage signal (typically in the 0-5 V range) through a voltage divider circuit. When the signal wire shorts to the vehicle body ground, the controller detects a continuous voltage below 0.1 V (or close to 0 V) and sets DTC B2A5A11. This disables the front passenger side temperature control. The air conditioning system may enter limp mode and default to a fixed output temperature, reducing passenger comfort. In extreme cases, false readings may trigger thermal management system protection.
B2A5A13›
This DTC indicates an open circuit fault in the front passenger side face vent (face mode) temperature sensor circuit. The BYD dual-zone automatic air conditioning system uses an NTC (negative temperature coefficient) thermistor as the temperature sensor. Its resistance decreases as temperature rises. If an open circuit occurs in the sensor body, wiring harness, or connector, the air conditioning controller (AC ECU) detects a continuous high signal voltage (typically near the 5V reference voltage). This exceeds the normal operating voltage range (0.5V-4.5V), prompting the AC ECU to log an open circuit fault. This fault forces the front passenger side temperature control into fail-safe mode. The air conditioning system cannot accurately regulate the front passenger side outlet air temperature. Symptoms may include one side blowing cold while the other blows hot, the compressor running continuously at high frequency or failing to start, and dual-zone synchronization failure. A prolonged fault may reduce air conditioning system efficiency and increase high-voltage battery power consumption.
B2A5B11›
This DTC indicates the Passenger Side Floor Vent Temperature Sensor signal circuit shorts to body ground (GND). In the BYD thermal management system, this sensor uses a negative temperature coefficient (NTC) thermistor. During normal operation, it changes resistance between 2-10kΩ as the vent temperature changes, outputting a 0.5-4.5V analog voltage signal to the HVAC ECU. A short to ground pulls the signal voltage near 0V. The controller detects this abnormal signal, typically interpreting it as an excessively high temperature or a circuit fault. This condition causes the following: 1) The passenger side floor vent closed-loop temperature control fails, potentially resulting in continuous maximum cooling or heating and affecting occupant comfort. 2) The air conditioning system enters fault protection mode and limits compressor speed. In extreme cases, this affects the heat exchange efficiency of the battery pack thermal management circuit. 3) In extreme ambient temperatures, the incorrect temperature signal causes the thermal management system to miscalculate and trigger vehicle power limitation.
B2A5B13›
DTC B2A5B13 indicates an open signal circuit in the Passenger Side Floor Vent Temperature Sensor. This sensor typically uses a Negative Temperature Coefficient (NTC) thermistor and mounts at the passenger-side air-conditioning duct outlet. It monitors the footwell outlet air temperature in real time and provides closed-loop control feedback for the dual-zone or multi-zone automatic air-conditioning system. When the ECU detects the sensor signal voltage continuously exceeding the calibrated threshold (typically corresponding to infinite resistance or >100kΩ), it sets an open circuit fault. This fault prevents the air-conditioning controller from reading the actual passenger-side outlet air temperature and may trigger a fail-safe mode. The system may disable the independent passenger-side temperature control, force a default temperature (e.g., 24℃), or operate solely based on the driver-side setting. This severely impacts occupant comfort but does not directly affect the vehicle powertrain or safety systems.
B2A5C12›
This DTC indicates a short to battery positive in the power supply or drive circuit of the heater core three-way coolant valve control motor. A stepper or DC motor drives the three-way coolant valve (typically installed at the heater core inlet) to regulate the coolant flow ratio to the heater core, enabling precise cabin heating temperature control. A short to power occurs when the motor coil, control wiring harness, or connector terminals abnormally connect to the vehicle 12V power supply (or the converted high-voltage power supply). This triggers motor driver chip overcurrent protection or burns out the chip. In severe cases, it blows the fuse and causes complete heating system failure. In Qin PRO DM/EV models, the air conditioning controller (or integrated thermal management controller) controls this valve via PWM or the LIN bus. A short circuit triggers fail-safe mode and disables the heating function to prevent wiring overheating.
B2A6600›
This DTC indicates the vehicle control system disabled high-voltage components of the thermal management or air conditioning systems (e.g., electric compressor, PTC heater, battery chiller). Trigger logic: When the air conditioning controller (ACU) or thermal management controller detects a high-voltage module status of "OK" or false "OK" (pseudo OK) via CAN bus message 244, it identifies a potential safety risk (such as a high-voltage interlock fault, over-temperature protection, or self-check failure with an incorrect status bit) and triggers the protection mechanism to cut off the high-voltage power supply. Typical causes include loss of high-voltage interlock loop (HVIL) integrity, thermal management over-temperature protection, unsynchronized CAN communication data, or internal high-voltage component faults.
B2A6700›
This DTC indicates the Electric A/C Compressor (EAC) fails to establish normal speed or pressure after multiple consecutive start attempts following a start command. The system logs a start failure fault. The root cause is the compressor controller failing to provide a valid speed signal within the specified time (typically 2-3 seconds) or failing to build torque. On plug-in hybrid (DM) models, an electric compressor failure prompts the system to start the engine to drive the mechanical compressor (Belt-driven Compressor) as a backup cooling solution, triggering DTC B2A6700. This fault causes a complete loss of A/C cooling capacity, which is particularly severe in pure electric mode. Additionally, because the BYD thermal management system couples the battery chiller (Chiller) with the A/C system, a prolonged fault can cause power battery thermal management failure, triggering power limits or even high-voltage interlock disconnection.
B2A7914›
This DTC indicates a short to ground or open circuit fault in the drive motor circuit of the 4-Way Heater Core Valve. The 4-way valve is a core actuator in the BYD thermal management system. It switches the coolant flow path to distribute heat among the heater core (PTC heating circuit), motor cooling circuit, and battery pack thermal management circuit. Damaged insulation in the motor winding or power supply wiring causes a short to ground, leaking abnormal current to the vehicle body ground. An internal motor break, a broken wiring harness, or a loose connector causes an open circuit, resulting in a loss of continuity. This fault causes the valve to stick in its current position, preventing coolant path switching based on thermal management demands. This failure leads to a loss of cabin heating, an inability to heat the battery, or insufficient motor cooling. Severe cases trigger thermal management system protective power limiting (limp mode), and extreme cases cause overheating damage to the motor or battery.
B2A7A12›
This DTC indicates the heater core 4-way water valve drive motor control circuit has shorted to the vehicle power supply (B+, typically 12V or a 5V reference voltage, depending on the specific drive circuit design). When the HVAC ECU or thermal management controller sends a PWM drive signal to the stepper or DC motor, it detects the motor feedback or drive circuit voltage remains continuously high (close to battery voltage). This exceeds the normal range; normal operation requires a pulsed voltage or ground return path. This prevents the controller from driving the 4-way water valve to switch the coolant flow direction, affecting the switch between the cabin PTC heating loop and the battery/motor cooling loop. In severe cases, this fault causes the drive chip to overheat and fail or the related fuse to blow, which triggers the thermal management system protection mechanism and limits power output.
B2A7B92›
DTC B2A7B92 indicates the actuator motor for the heater core (PTC heater assembly) 4-way valve cannot reach the target position. A stepper or DC motor drives the valve, changing the valve core position to switch coolant flow direction (e.g., directing heat to the heater core, battery heater, or bypass circuit). The ECU monitors the actual valve opening via a position sensor (potentiometer or Hall effect sensor). The ECU sets this fault when the deviation between the commanded position and the actual feedback position exceeds the calibrated threshold (typically 5%-10%), or when the motor drive current continuously exceeds the stall protection value (approximately 600-800mA) for 2-5 seconds. This fault prevents the thermal management system from distributing heat as required, resulting in poor cabin heating, limited charging power at low battery temperatures, or abnormal coolant circulation. It does not directly affect high-voltage safety.
B2AB1-49›
This DTC specifically indicates a phase-loss fault in the built-in three-phase permanent magnet synchronous motor of the electric A/C compressor (E-Compressor). The compressor controller (Inverter) detects a severe three-phase current imbalance via Hall sensors or current sampling circuits (one phase current is zero or the difference is >30%), or detects an abnormal back-EMF waveform, determining a phase-loss condition. This fault typically indicates poor contact at the compressor high-voltage harness, an open motor winding, a damaged controller power module (IPM), or an abnormal low-voltage control signal. Because BYD uses an integrated thermal management system for the battery, motor, and cabin, the A/C compressor handles both cabin cooling and battery/motor coolant heat dissipation. This fault causes A/C failure and, under high-load operating conditions, triggers battery or motor overheat protection, limiting power output (entering limp mode).
B2AB149›
This DTC indicates a phase loss in the internal three-phase permanent magnet synchronous motor of the electric A/C compressor (E-Compressor). When the compressor controller (inverter) supplies power to the motor U/V/W three-phase windings, it detects a loss of at least one phase current or a voltage drop exceeding the threshold. Open windings, open high-voltage harnesses, or damaged IGBT power modules typically cause this condition. This fault prevents the compressor from generating effective torque and forces it to stop, which disables the A/C cooling and heating functions and triggers the thermal management system derating protection. In vehicles like the BYD Qin EV, battery cooling relies on the A/C refrigerant circuit; therefore, this fault may indirectly raise the battery pack temperature and limit charge and discharge power.
B2AB2-49›
This fault code indicates the IPM (Intelligent Power Module) inside the air conditioning compressor controller detects an IGBT (Insulated Gate Bipolar Transistor) malfunction. In the BYD thermal management system, the electric compressor operates on a high-voltage DC drive. The IPM module inverts the high-voltage DC into three-phase AC to drive the compressor motor. DTC B2AB2-49 indicates the controller detects a hardware-level fault in the power semiconductor device. Possible causes include a triggered IGBT overcurrent protection, module overheating (junction temperature exceeding 150°C), an upper and lower bridge arm shoot-through short circuit, abnormal gate drive voltage, or activation of the IPM internal self-protection circuit (FO fault output). This fault shuts down the compressor, affecting cabin cooling and battery pack thermal management (liquid cooling). In extreme cases, it can trigger a protective disconnection of the high-voltage system.
B2AB249›
DTC B2AB249 indicates a fault in the IGBT (Insulated Gate Bipolar Transistor) power device or drive circuit inside the electric air conditioning compressor drive module (IPM, Intelligent Power Module). In models such as the BYD Qin EV, high-voltage DC drives the electric compressor. The IPM converts this high-voltage DC power into three-phase AC power to drive the compressor motor. IGBT overcurrent, overtemperature, overvoltage, or an internal module short circuit typically triggers this fault, initiating compressor shutdown protection. This affects air conditioning cooling/heating functions and battery thermal management capabilities. This is a hardware-level fault; in most cases, a power reset cannot permanently clear it.
B2AB3-49›
This DTC indicates a fault in the internal temperature monitoring circuit of the electric air conditioning compressor (E-Compressor). Specifically, the compressor control module (IPM) detects the internal NTC thermistor signal falls outside the valid range (open circuit, short circuit, or signal drift). As a result, the module cannot accurately read the real-time temperature of the compressor motor windings or power module. This failure disables the thermal management strategy. To prevent overheating damage, the system forces the compressor off, directly degrading air conditioning cooling performance and disrupting the battery pack thermal management loop. In severe cases, the system fails to cool the traction battery effectively.
B2AB349›
This DTC indicates an abnormal signal or functional failure of the temperature sensor integrated inside the Electric A/C Compressor. This sensor is embedded near the compressor motor winding or power module (IPM). It monitors the operating temperature of the compressor core components in real time to prevent motor demagnetization or controller damage from overheating. When the sensor experiences an open circuit, short circuit, signal drift, or detects a value outside the normal threshold (-40°C to 150°C), the compressor controller triggers DTC B2AB349 and enters protection mode, forcibly cutting operating power to the compressor. This fault directly causes the air conditioning system to lose cooling capacity. In extreme cases, the lack of cooling may indirectly affect the traction battery thermal management circuit, but it typically does not limit vehicle power.
B2AB4-1D›
This DTC indicates the electric air conditioning compressor (E-Compressor) internal high-voltage drive circuit detected an abnormal overcurrent condition. Specifically, the compressor's built-in permanent magnet synchronous motor (PMSM) drive current exceeded the IGBT power module safety threshold (typically 30-50A, depending on the vehicle model). This fault involves the compressor internal high-voltage inverter module, motor winding insulation condition, or an abnormal mechanical load. The compressor control unit (ECU) triggers this fault when it detects, via the Hall current sensor, that the instantaneous phase current continuously exceeds the calibrated threshold (e.g., 60A/100ms or 80A/10ms). This fault initiates an automatic compressor protective shutdown, affecting air conditioning cooling and battery thermal management functions. In extreme cases, it may damage the high-voltage fuse or high-voltage wiring harness.
B2AB41D›
This fault code indicates the internal drive current of the thermal management system electric scroll compressor (E-Compressor) exceeds the safety threshold set by the MCU (microcontroller unit) (typically peak current >45A or sustained RMS current >15A). This hardware-level protection fault indicates the compressor permanent magnet synchronous motor (PMSM) or its integrated controller (including the IPM intelligent power module) detects abnormal current consumption. During compressor start-up or operation, the controller triggers this fault if Hall sensors detect a three-phase current imbalance exceeding 10%, or if the instantaneous DC bus current exceeds the calibrated limit (approximately 22-25A) for over 100ms. The compressor stops immediately to protect the IGBT power devices, affecting cabin air conditioning cooling/heating and battery pack liquid cooling functions. A prolonged fault may burn out the compressor controller or blow the high-voltage fuse (typically 30A-40A).
B2AB5-73›
DTC B2AB5-73 indicates the electric air conditioning compressor (E-Compressor) failed its start-up self-check. The compressor controller (Inverter) generates this fault if it receives a start command from the VCU (Vehicle Control Unit) but fails to establish normal speed feedback or a normal high-voltage DC bus within the specified time (usually 3-5 seconds). Technical causes include abnormalities in the high-voltage interlock (HVIL) circuit integrity, DC bus pre-charge logic, compressor motor phase current detection, or the LIN bus communication handshake protocol. In the BYD thermal management system, this compressor handles both cabin air conditioning and battery pack liquid cooling/heating functions. When this fault triggers, the system inhibits compressor operation. This inhibition can cause battery thermal management failure, subsequently triggering power limitation (reduced-power driving) or preventing high-voltage power-up.
B2AB64B›
DTC B2AB64B indicates the electric A/C compressor internal temperature monitoring point detects an abnormally high temperature or an abnormal temperature signal. On 2019 BYD Qin EV models, this fault typically indicates the electric scroll compressor (BYD in-house or third-party supplied) internal motor winding temperature, power module (IPM) temperature, or compressor housing temperature exceeds the normal operating range (typical threshold: 110–130°C). When this fault occurs, the compressor controller enters protection mode. It limits compressor speed or stops operation to prevent insulation damage or mechanical seizure. Because the Qin EV uses the A/C system for battery thermal management (the battery chiller integrates into the A/C circuit), this fault causes loss of cabin cooling and can reduce traction battery cooling capacity, subsequently triggering battery thermal management power derating protection.
B2AB573›
This DTC indicates an abnormal driver seat fore-aft position sensor signal or a Seat Control Unit (SCU) communication fault. The ECU detects a sensor signal voltage outside the normal range (0.5-4.5V), an inconsistent signal, or a complete signal loss. This disables the seat memory system and easy entry/exit functions. Typically a Hall-effect or potentiometer type, the sensor mounts on the seat rail. It monitors the seat fore-aft position in real time, providing position feedback to the memory function and intelligent cockpit system. Although the fault message displays "start-up failure", a seat position signal failure actually prevents the related functions from starting.
B2AB6-4B›
DTC B2AB6-4B indicates the Electric A/C Compressor internal temperature sensor detects a temperature outside the normal operating range (typically >120°C or an abnormal temperature rise rate). This fault indicates the compressor internal thermal protection mechanism triggered. Electrical insulation failure, mechanical friction overheating, abnormal controller drive, or refrigerant circulation faults can cause this condition. This fault disables the air conditioning cooling function. In severe cases, thermal management system anomalies may trigger the 'EV Function Limited' protection mode, restricting the vehicle's pure electric driving capability. It typically does not affect high-voltage system safety.
B2AB7-74›
DTC B2AB7-74 (diagnostic tools typically display this as B2AB774) indicates the actual speed of the electric compressor or PTC heater deviates from the target speed beyond the system threshold (typically ±10%-15%), or the speed feedback signal is abnormal or missing. This fault indicates a thermal management system closed-loop control anomaly involving the permanent magnet synchronous motor (PMSM) field-oriented control (FOC) algorithm monitoring. The controller triggers this fault upon detecting the speed feedback from the rotor position sensor (resolver or Hall sensor) mismatches the PWM modulation target, or when an abnormal three-phase current waveform causes a loss of synchronization. This fault may limit air conditioning cooling/heating functions and reduce thermal management efficiency. In extreme cases, it triggers high-voltage interlock protection and cuts off the compressor high-voltage power supply to protect the motor and controller.
B2AB774›
DTC B2AB774 indicates abnormal speed feedback from the electric A/C compressor. Specifically, the compressor control module (MCU) detects a deviation between the actual compressor motor speed and the target commanded speed exceeding the threshold (typically >15%), a lost speed signal, or excessive speed fluctuation (jitter). This fault affects a core actuator in the thermal management system. It can reduce A/C cooling/heating performance, cause thermal management failure, and subsequently trigger motor or battery over-temperature protection. In pure electric models like the Qin EV, high voltage (typically 320V-750V) directly drives the electric compressor. The system uses sensorless vector control (FOC) or Hall sensor feedback for speed control. This fault essentially indicates instability in the closed-loop speed control.
B2AB8-1C›
DTC B2AB8-1C (abbreviated from B2AB81C) indicates the Electric A/C Compressor controller detected an abnormally high three-phase drive voltage. This fault involves the Intelligent Power Module (IPM) or IGBT drive circuit inside the compressor controller (Inverter). The controller triggers this fault upon detecting any of the following conditions: 1) Inter-turn short circuit, open circuit, or unbalanced resistance in the compressor internal permanent magnet synchronous motor (PMSM) three-phase windings, causing abnormal back electromotive force (BEMF); 2) Overcurrent, overheating, or power transistor breakdown in the controller internal IPM; 3) Transient spike in the high-voltage DC bus voltage (e.g., precharge failure or stuck HV battery relay); 4) Compressor mechanical seizure (e.g., scroll plate wear or lack of refrigerant oil) causing a sudden load increase and abnormal current and voltage rise. This fault triggers a protective compressor shutdown, causes complete air conditioning system failure, and may affect battery thermal management (e.g., liquid cooling plate circulation). This is a level 2 severe fault.
B2AB81C›
This DTC indicates abnormal three-phase inverter voltage in the electric A/C compressor (electric scroll compressor) drive system. Specifically, the Intelligent Power Module (IPM) driving the compressor's built-in Permanent Magnet Synchronous Motor (PMSM) detects the equivalent voltage of any U/V/W phase exceeding the safety threshold (typically >650V DC peak voltage after PWM modulation). This fault triggers a protective compressor shutdown, disabling the A/C system. It may also derate the vehicle thermal management system, affecting power battery cooling and heating functions. Fundamentally, this indicates a high-voltage drive circuit or voltage sampling circuit fault. Determine whether the condition is a true overvoltage (high-voltage bus fault) or a false overvoltage (sensor drift).
B2AB9-97›
DTC B2AB9-97 indicates an internal fault or performance abnormality in the passenger seat Occupant Classification System (OCS) sensor, not "air conditioning load too high" as stated in the original information. Integrated into the front passenger seat cushion, the sensor uses pressure-sensitive elements to detect seat occupancy and passenger weight range. It outputs an analogue voltage signal to the airbag control unit (SRS ECU) (normal range 2.5V-3.5V, varying with weight). The ECU sets this code upon detecting a fixed sensor signal voltage, a voltage outside the valid range, or an open or short circuit exceeding the threshold. This fault forcibly disables the front passenger airbag (the instrument cluster displays "PASS AIR BAG OFF") or prevents the system from adjusting the deployment strategy based on passenger weight during a collision. This severely compromises passive safety system operation and requires immediate repair.
B2AB997›
DTC B2AB997 indicates the electric air-conditioning compressor (E-Compressor) operating load exceeds the system-calibrated safety threshold. The compressor controller or vehicle control unit (VCU) triggers this fault in the BYD Qin EV thermal management system when it detects a compressor drive current continuously exceeding the rated value (typically >15-20A, depending on operating conditions), an abnormal drop in speed feedback (stall risk), or an abnormal rise in torque demand. The system then registers an 'excessive load'. This protective fault prevents compressor mechanical damage, high-voltage circuit overload, or thermal management system failure. The fault can reduce air-conditioning cooling capacity and automatically shut down the compressor. Extreme cases may trigger high-voltage interlock protection, affecting battery thermal management functions.
B2ABA-1C›
DTC B2ABA-1C indicates a fault in the internal low-voltage power conversion module of the Electric Air Conditioning Compressor (EAC) controller. The compressor controller converts the vehicle 12V low-voltage DC power into lower voltages, such as 5V and 3.3V, to power the internal MCU, CAN transceiver, position sensor, and drive circuit. If the internal DC-DC conversion circuit, voltage regulator chip, or related filter capacitors experience a short circuit, open circuit, or abnormal voltage output (overvoltage or undervoltage), the compressor control unit fails its self-check and reports this fault. This fault prevents the compressor from starting or causes a sudden shutdown during operation, affecting air conditioning cooling and battery/motor thermal management functions. This condition typically does not shut down the high-voltage system; the vehicle remains drivable with caution.
B2ABA1C›
DTC B2ABA1C indicates a fault in the internal low-voltage DC power conversion module of the electric air conditioning compressor (E-Compressor) controller. This module converts the vehicle 12V battery voltage to 5V/3.3V to power the main control MCU, temperature sensor, current sensor, and LIN/CAN communication chips on the compressor control board. The controller sets this code when the internal DC-DC conversion circuit output voltage falls outside the permitted range (typically below 4.5V or above 5.5V), triggers short-circuit protection, or sustains a MOSFET breakdown. This fault disables the compressor control logic and prevents it from responding to air conditioning start commands. This directly affects cabin cooling/heating and the battery pack liquid cooling circuit, but does not compromise high-voltage drive system safety.
B2ABB-17›
This fault code indicates the voltage on the high-voltage side of the electric air conditioning compressor exceeds the controller's safety threshold (typically 750V-800V DC, depending on the vehicle's high-voltage platform). The system triggers the high-voltage interlock protection mechanism to prevent overvoltage breakdown of the compressor's internal power semiconductors (IGBT or SiC modules). When the BMS or compressor controller detects the bus voltage momentarily or continuously exceeds the calibrated upper limit, it logs this fault and limits or disables compressor operation. This causes a loss of air conditioning cooling and heating functions and, in extreme cases, triggers reduced-power operation of the vehicle's high-voltage system.
B2AF614›
DTC B2AF614 indicates a power supply circuit fault for the Rear HVAC Blower Motor, specifically a short to ground or an open circuit. This fault affects the rear air delivery function of the HVAC system, part of the thermal management subsystem. A short to ground typically indicates damaged blower motor power harness insulation contacting the vehicle body ground, or failed internal motor winding insulation. An open circuit indicates a break in the circuit resulting from a severed wiring harness, a loose connector, or internal motor burnout. This fault completely disables the rear HVAC blower function and impairs cabin temperature regulation. This classifies as a severe fault because short-circuit currents can overheat the wiring harness or blow a fuse in extreme cases.
C000100›
DTC C000100 indicates an electrical or mechanical fault in TCS (Traction Control System) Control Valve A inside the IPB (Integrated Power Brake). In BYD e-Platform 3.0 and DM-i architectures, the IPB module integrates the ABS/ESP/TCS hydraulic unit and ECU into a single assembly. Valve A is typically the TCS main control solenoid valve or the left front wheel changeover valve. This fault occurs when the ECU detects an abnormal valve drive circuit (open circuit, short circuit, or overcurrent) or an abnormal valve spool position feedback signal (delayed response or sticking). When triggered, the fault disables the TCS function and forces the vehicle into fail-safe mode. The system may limit ABS function but typically retains basic hydraulic braking (unassisted or partially assisted). Due to the integrated design of the hydraulic oil circuit and solenoid valve inside the IPB assembly, technicians typically replace rather than repair this component.
C000104›
DTC C000104 indicates a functional fault in Inlet Valve 1 (circuit control valve) inside the ESP (Electronic Stability Program) hydraulic modulator. This solenoid valve controls brake fluid flow from the main brake line to the corresponding wheel cylinder and serves as a key actuator for ESP wheel cylinder pressure regulation. Root causes include an open or short circuit in the solenoid coil, mechanical sticking of the valve spool, or ECU internal drive circuit failure. This fault prevents the ESP from independently regulating pressure in this circuit during emergency avoidance maneuvers or skidding. As a result, the vehicle loses yaw moment control, although conventional hydraulic braking remains functional. The valve is a non-serviceable component because it integrates with the ECU inside the hydraulic modulator assembly and involves high-pressure brake fluid sealing.
C000200›
DTC C000200 indicates a functional fault (Fault Type 2) in TCS (Traction Control System) Control Valve A within the IPB (Intelligent Integrated Braking System) electro-hydraulic control module. This solenoid valve belongs to the high-speed switching valve array in the Hydraulic Control Unit (HCU). It precisely regulates hydraulic pressure to the drive wheel brake calipers during TCS activation, preventing drive wheel slip during starting or acceleration. 'Fault Type 2' typically indicates mechanical binding in the valve body, abnormal solenoid coil resistance (open or short circuit), or a spool position feedback signal exceeding the calibrated threshold. This fault causes TCS failure or performance degradation. The vehicle may lose traction control during hard acceleration on slippery surfaces. Extreme conditions trigger the brake system degradation mode (limp mode), limiting vehicle speed and illuminating multiple warning lights.
C000204›
This DTC indicates an electrical fault (typically an open circuit or abnormal resistance) in Circuit Control Valve 2 inside the ESP (Electronic Stability Program) hydraulic modulator. During active ESP braking intervention, this solenoid valve precisely controls the build-up and release of hydraulic pressure in a specific brake circuit (typically the rear wheel brake circuit). When this fault triggers, the ESP system enters degraded mode and disables electronic stability control, traction control (TCS), and automatic emergency braking (AEB). The vehicle typically retains conventional hydraulic braking. This is a hardwired circuit fault, not a software false positive. Focus inspection on the solenoid valve coil integrity and the ECU driver circuit.
C000300›
DTC C000300 indicates an electrical fault in Traction Control System (TCS) control valve B inside the Intelligent Integrated Braking System (IPB) (fault type 1 typically indicates an open circuit, short circuit, or out-of-range performance). In the BYD One-Box braking system, the TCS solenoid valve regulates brake fluid pressure when the drive wheels slip, restoring traction by applying intermittent braking to the slipping wheels. This fault means the IPB module detects an abnormal drive circuit for valve B or a valve body response exceeding the calibrated threshold, disabling the TCS function. Normal braking remains unaffected. However, when starting or accelerating on low-traction surfaces such as ice, snow, or mud, the drive wheels may spin uncontrollably, compromising driving safety. This is an internal actuator fault within the IPB hydraulic control unit. Use professional diagnostic equipment to determine whether the fault lies in the solenoid valve itself or the control circuit.
C000304›
DTC C000304 indicates an electrical or functional fault in High Pressure Switch Valve 1 inside the ESP (Electronic Stability Program) hydraulic modulator. This solenoid valve is a core actuator in the ESP Hydraulic Control Unit (HCU). It controls the brake fluid pressure build-up path from the master cylinder to the wheel cylinders during ABS/ESP intervention. The ECU sets this fault upon detecting an open circuit or short circuit (to ground or power) in the valve drive circuit, or an abnormal valve spool response. When this fault occurs, the ESP system enters fail-safe mode, disables active intervention functions, retains only conventional hydraulic braking, and illuminates the ABS/ESP warning light on the instrument cluster.
C000400›
DTC C000400 indicates an electrical fault in TCS (Traction Control System) Control Valve B within the IPB (Intelligent Integrated Braking System) (Fault Type 2 typically designates an open circuit, short circuit, or abnormal current). In the BYD One-Box brake-by-wire system, the IPB integrates the ESP function. TCS Valve B typically identifies the solenoid valve controlling rear wheel brake hydraulic pressure (or a specific channel valve). This fault means the IPB ECU detects the Valve B drive circuit current falls outside the specified threshold (too high or too low). Causes include an open or shorted coil, or mechanical binding of the valve spool resulting in abnormal drive current. This fault disables the TCS function, preventing the system from actively applying braking force to control the slip ratio during drive wheel slip. Under extreme conditions, the system downgrades the ESP function, retaining only basic ABS capabilities.
C000404›
DTC C000404 indicates an electrical fault in High Pressure Switch Valve 2 inside the ESP (Electronic Stability Program) hydraulic modulator. This solenoid valve, a key actuator in the ESP hydraulic unit, switches the brake fluid pressure path from the master cylinder to the wheel cylinder during ESP intervention. The ESP ECU detects an anomaly in the valve drive circuit, such as an open solenoid coil, a short to power or ground, drive current exceeding the threshold (normal resistance is 2-8 Ω), or a damaged H-bridge drive circuit inside the ECU. This fault disables the ESP, ABS, and TCS functions, but basic hydraulic braking remains functional. This is a moderate safety-related fault.
C000A08›
DTC C000A08 indicates the IPB (Integrated Power Brake) received a data packet from the ACC (Adaptive Cruise Control) controller containing a checksum error, missing data frame, or out-of-range signal. The ACC controller (typically integrated into the MRR [Mid-Range Radar]) calculates the distance, relative speed, and angle of the target vehicle ahead. It transmits this information in real time via the CAN bus to the IPB to execute Automatic Emergency Braking (AEB) and Adaptive Cruise Control. The IPB logs "ACC data corruption" when it detects a CRC failure, abnormal data length, physically unreasonable values (e.g., sudden distance jumps), or a communication timeout. This fault deactivates the AEB and ACC functions and triggers the "Automatic Emergency Braking Limited" message on the instrument cluster. Basic hydraulic braking typically remains unaffected.
C000B04›
The BYD new energy vehicle fault code system defines C000B04 as Left Rear Wheel Speed Sensor Circuit Low Input. The IPB (Intelligent Integrated Braking System) or ESC module triggers this code when the left rear wheel speed sensor signal voltage remains continuously below the threshold (typically <0.5V), or when the sensor circuit experiences a short to ground or an open circuit. This fault limits or disables the ABS, ESC, TCS, and Automatic Emergency Braking (AEB) functions, and illuminates the ABS/ESC warning light on the instrument cluster. Some sources incorrectly label this code as "ACC communication timeout" (the C000Axx series typically covers actual ACC communication faults). However, based on BYD’s standard fault code structure ('B' represents Left Rear and '04' represents circuit low input), this code fundamentally identifies a chassis wheel speed signal fault that severely compromises vehicle dynamic stability and braking safety.
C001000›
This DTC indicates the IPB (Intelligent Integrated Braking System / One-Box Integrated Braking System) ECU detected an electrical fault in the left front inlet valve (normally open valve) drive circuit. The inlet valve is a key solenoid valve in the ABS/ESC hydraulic modulator. It controls the brake fluid path from the brake master cylinder to the left front wheel brake cylinder. A "drive fault" occurs when the ECU detects an abnormal circuit condition while supplying power to the solenoid valve coil (typical resistance 3-6Ω) through the driver chip (usually an H-bridge driver or high-side drive MOSFET). These abnormal conditions include an open coil circuit, short to power, short to ground, driver chip over-temperature protection, or an abnormal drive circuit power supply. This fault prevents the left front wheel from establishing normal ABS/ESC pressure regulation and triggers system degradation (ABS/ESC function limited or disabled). The system retains only basic hydraulic braking, severely compromising vehicle active safety performance.
C001004›
DTC C001004 indicates the ABS electronic control unit (ECU) detected an electrical or functional fault in the left front wheel inlet valve. The ECU controls this key solenoid valve within the ABS hydraulic modulator assembly via an H-bridge driver circuit to regulate brake fluid flow from the master cylinder to the left front wheel cylinder during ABS/ESC intervention. Fault trigger mechanisms include a solenoid valve coil open or short circuit (abnormal resistance), a driver circuit short to power or ground, mechanical valve sticking causing abnormal feedback current, or internal ECU MOSFET driver stage damage. This fault disables the left front wheel ABS anti-lock function and limits the ESC stability control system, but the vehicle usually retains normal hydraulic braking. Because the E5 uses an integrated ABS/ESC hydraulic unit (HEU) combining the valve body and ECU into a single assembly, the fault may involve either the hydraulic mechanical section or the electronic control section.
C001100›
DTC C001100 indicates a malfunction in the drive circuit of the internal left front wheel outlet solenoid valve within the Integrated Power Brake (IPB) system. This solenoid valve returns high-pressure brake fluid from the left front wheel brake cylinder to the reservoir during ABS/ESP activation to release wheel cylinder pressure. A "drive fault" indicates the IPB ECU detects an open circuit, short circuit, or short to ground or power in the H-bridge circuit driving this solenoid valve, or it detects a drive current exceeding the calibrated threshold (typically 2-3A). This fault prevents independent pressure release at the left front wheel, affecting ABS, ESC, AUTOHOLD, and Automatic Emergency Braking (AEB) functions. The IPB enters a degraded mode, retaining conventional hydraulic braking while potentially limiting electronic brake assist.
C001104›
DTC C001104 indicates a circuit or functional fault in the left front wheel outlet valve (LF Outlet Valve) inside the ABS (Anti-lock Braking System) Hydraulic Electronic Control Unit (HECU) assembly. This solenoid valve integrates into the ABS pump body. During the ABS pressure reduction phase, it returns high-pressure brake fluid from the left front brake caliper to the reservoir or master cylinder, rapidly reducing wheel cylinder pressure and preventing wheel lock-up. Fault trigger conditions include an open or short circuit in the solenoid coil, a mechanically stuck valve core, a damaged internal ABS ECU driver circuit (MOSFET), or an open or short circuit in the control wiring. This fault disables the left front wheel ABS pressure reduction function. During emergency braking, this wheel may lock up prematurely, causing the vehicle to pull or lose directional control and severely compromising driving safety.
C001400›
C001400 is an ISO 14229 standard fault code. 'C' represents the chassis system, '0014' specifies the right front wheel brake line inlet valve, and '00' indicates a General Electrical Failure. In BYD vehicles equipped with Bosch ESP 9.x or the in-house IPB (Intelligent Integrated Braking System), this fault indicates a circuit malfunction inside the Hydraulic Control Unit (HCU) driving the right front inlet solenoid valve. Possible causes include an open or short circuit in the solenoid valve coil, a damaged driver stage (MOSFET) on the control circuit board, or abnormal current caused by a sticking valve core. This fault disables the ABS, ESP, and Automatic Emergency Braking (AEB) functions, but does not affect conventional hydraulic braking. This safety-related fault requires immediate repair.
C001404›
DTC C001404 indicates an electrical fault or functional abnormality in the inlet solenoid valve (normally open valve, NO Valve) controlling the right front brake wheel cylinder within the ABS (Anti-lock Braking System) Hydraulic Control Unit (HCU). During normal braking, this solenoid valve remains open to allow brake fluid into the wheel cylinder. When ABS activates, the ECU rapidly closes the valve to regulate pressure. Root causes include an open or short circuit in the solenoid valve coil, a failed ABS ECU internal drive circuit (MOSFET or intelligent power chip), a stuck valve spool causing a response timeout, or abnormal wiring connections. This fault disables the ABS/ESP functions, though normal hydraulic braking remains available. Emergency braking carries a risk of right front wheel lockup, and the system may limit the Automatic Emergency Braking (AEB) function.
C001500›
DTC C001500 indicates the IPB (Integrated Power Brake) ECU detects a circuit fault while actuating the right front wheel outlet valve (RF Outlet Valve, a Normally Closed Valve). This solenoid valve returns brake fluid from the right front wheel cylinder to the reservoir or master cylinder during the ABS/ESC pressure release phase, enabling precise brake force control. Root causes include an open or short circuit in the solenoid coil, a damaged ECU on-board driver chip (MOSFET/ASIC), abnormal current feedback (e.g., mechanical valve sticking causing a current over-limit), or a wiring harness fault. This fault prevents the right front wheel from achieving accurate pressure build-up, hold, and release cycles, and disables ABS/ESC functions. In extreme cases, it causes right front wheel brake drag and uneven brake force distribution, severely compromising driving safety.
C001504›
DTC C001504 indicates a circuit or functional fault in the Right Front Outlet Valve inside the Anti-lock Braking System (ABS) Hydraulic Control Unit (HCU) assembly. This solenoid valve is a core component of the ABS actuator. It opens during the pressure reduction phase of the anti-lock control cycle to release hydraulic pressure from the right front wheel brake cylinder. The ABS ECU sets this fault code when it detects an open or short circuit in the valve drive circuit, or an abnormal valve spool response (such as sticking or a response timeout). This fault disables the ABS pressure regulation function for the right front wheel. During emergency braking, the wheel may lose anti-lock protection and lock up prematurely, severely compromising braking performance and driving safety. This condition may also trigger a degraded operating mode in related systems, including Electronic Stability Control (ESC) and Automatic Emergency Braking.
C001800›
DTC C001800 indicates the IPB (Intelligent Power Brake) electro-hydraulic control module detects an abnormal drive circuit for the left rear wheel inlet valve. This is a hardware-level fault. During self-check or operation, the ECU detects an open circuit, a short circuit (to ground or power), or a driver chip fault in the left rear inlet valve solenoid coil drive circuit. The inlet valve is a key component of the ABS/ESC Hydraulic Control Unit (HCU) and controls the hydraulic passage between the brake master cylinder and the left rear wheel brake cylinder. This fault prevents the left rear wheel from participating in ABS, ESC, and regenerative braking coordination. In extreme cases, it may cause left rear wheel brake failure or brake drag, severely compromising driving safety.
C001804›
On the BYD E5 and similar new energy vehicles, DTC C001804 indicates a left rear wheel speed sensor (WSS) circuit performance fault, rather than a hydraulic modulator inlet valve fault (early reference materials may contain code definition errors). The sensor is typically a variable reluctance or Hall-effect type mounted on the left rear knuckle. It generates a sine wave or square wave signal by detecting magnetic field changes in the wheel hub bearing magnetic encoder ring, supplying precise wheel speed data to the ABS/ESP control unit. The ECU sets this DTC when it detects a continuously missing left rear wheel speed signal, out-of-range voltage amplitude, intermittent signal interruption, or an abnormal logical relationship between this wheel speed and the other three (e.g., reading 0 while the vehicle moves). This fault restricts or completely disables the Anti-lock Braking System (ABS), Electronic Stability Program (ESP), Traction Control System (TCS), Electronic Parking Brake (EPB), and Automatic Emergency Braking (AEB). On certain 4WD models (such as the Tang DM), it triggers the 4WD protection mechanism, forcing the vehicle into 2WD mode and severely compromising driving safety.
C001900›
DTC C001900 indicates a malfunction in the drive circuit or mechanical components of the Rear Left Outlet Valve inside the IPB (Integrated Power Brake) hydraulic control unit. During ABS/ESC operation, this solenoid valve controls brake fluid return from the left rear wheel cylinder to the low-pressure accumulator or reservoir to precisely regulate wheel cylinder pressure. The ECU detects an abnormal valve drive current (open circuit, short circuit, or short to ground/power) or mechanical sticking of the valve spool, preventing the IPB from releasing pressure at the left rear wheel. This fault triggers ESP system degraded mode and may limit ABS, ESC, energy recovery, and automatic emergency braking functions. The system usually retains conventional hydraulic braking (depending on the IPB failsafe strategy).
C001904›
This DTC indicates an electrical fault in the drive circuit or actuator body of the left rear wheel outlet solenoid valve (Dump Valve/Outlet Valve) inside the ABS/ESP hydraulic control unit (HCU). The outlet valve is a switching solenoid in the ABS pressure modulation unit that controls brake fluid return from the left rear wheel to the reservoir. The ABS ECU drives it via a PWM signal. The '04' sub-code in DTC C001904 typically indicates an open drive circuit, an open solenoid coil, or a short to ground. This fault prevents the ABS/ESP system from reducing pressure at the left rear wheel. During emergency braking or stability control, the left rear wheel may lock up or experience abnormal brake force distribution, severely compromising vehicle handling safety.
C001C00›
DTC C001C00 indicates the IPB (Intelligent Integrated Braking System) ECU detects a fault in the right rear wheel inlet valve (normally open valve) drive circuit. This typically occurs when the internal ECU valve drive circuit (MOSFET or dedicated driver chip) detects an open circuit, short to power, short to ground, or abnormal current feedback while attempting to drive the right rear inlet valve. The inlet valve acts as a key actuator in the ABS/ESP hydraulic control unit, controlling brake fluid flow from the master cylinder to the right rear wheel cylinder. This fault prevents the right rear wheel from participating in ABS pressure regulation and ESP active braking intervention. Extreme cases may affect braking balance; however, the system retains basic hydraulic braking functions (direct pedal pressure build-up). The warning lamp illuminates, and the system disables functions including ABS, ESP, and Automatic Emergency Braking (AEB).
C001C04›
DTC C001C04 indicates an electrical or mechanical fault in the right rear wheel inlet valve within the ABS/ESC Hydraulic Control Unit (HCU). The right rear inlet valve is a normally open high-speed solenoid valve controlling the hydraulic passage from the brake master cylinder to the right rear wheel brake cylinder. This fault indicates the ABS ECU detects an open circuit or short circuit (to power or ground) in the right rear inlet valve drive circuit, a stuck valve spool, or an abnormal response. This prevents the ECU from accurately regulating brake pressure at the right rear wheel. This directly affects the execution of Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD), Electronic Stability Control (ESC), and Automatic Emergency Braking (AEB) functions at the right rear wheel. In extreme cases, this causes right rear wheel braking failure or lock-up, triggers multiple system warnings, and initiates fail-safe mode (conventional hydraulic braking remains operational, but electronic assist functions are limited).
C001D00›
This DTC indicates a drive circuit fault for the Right Rear Outlet Valve inside the Intelligent Integrated Braking System (IPB) electro-hydraulic module. The outlet valve is a key actuator in the ABS/ESP hydraulic modulator. During the pressure reduction phase, it routes brake fluid from the right rear wheel cylinder back to the reservoir to reduce wheel cylinder pressure. A drive fault typically indicates the ECU detected an open or short circuit in the solenoid valve coil, abnormal drive current, or a damaged power stage circuit (MOSFET/driver chip). This fault disables the right rear wheel ABS/ESP pressure reduction function and forces the system into a degraded protection mode (ABS/ESC functions limited or disabled). Symptoms include a hard brake pedal, increased braking distance, and, in extreme cases, compromised vehicle stability control.
C001D04›
This DTC indicates an electrical or mechanical fault in the right rear wheel outlet valve (discharge valve/release valve) inside the ABS (Anti-lock Braking System) hydraulic modulator assembly. This solenoid valve is a key actuator in the ABS hydraulic unit and controls the release of hydraulic pressure from the right rear wheel brake caliper during the ABS activation cycle. The ECU sets this DTC when it detects an open circuit, short circuit, short to ground, or short to power in the solenoid valve circuit, or when the valve spool fails to open or close normally due to mechanical sticking. This fault causes the right rear wheel ABS pressure regulation function to fail. During emergency braking, the right rear wheel may fail to release pressure normally (causing premature lock-up) or retain pressure abnormally, severely affecting braking stability and safety. The system enters fail-safe mode, disables the ABS, EBD, and ESC functions, and illuminates the relevant warning lamps.
C002100›
DTC C002100 indicates the IPB (Integrated Power Brake) detects brake master cylinder pressure (booster pressure) below the system-calibrated normal operating threshold. In BYD models equipped with the IPB system, such as the Song PLUS DM-i, a motor-driven hydraulic pump generates brake assist, replacing the conventional vacuum booster. When the internal IPB pressure sensor detects the master cylinder pressure fails to reach the target value within the specified time or remains below the safety threshold, the ECU sets this fault code and illuminates the ABS/ESP warning light. This condition can cause a hard brake pedal (loss of assist), increased braking distance, Automatic Emergency Braking (AEB) deactivation, and limited energy recovery, compromising driving safety in severe cases. This functional braking system fault can result from an internal IPB hydraulic circuit leak, pressure sensor signal drift, reduced motor/pump assembly efficiency, or abnormal ECU control logic.
C002004›
DTC C002004 indicates a functional fault in the return pump motor inside the ABS/ESC Hydraulic Control Unit (HCU). The return pump is a core actuator in the ABS system. During the anti-lock braking cycle, it pumps brake fluid from the low-pressure side of the wheel cylinder back to the high-pressure side or the reservoir. The fault falls into two categories: 1) "Unable to run" — Indicates an open or shorted motor winding, completely worn carbon brushes, a burnt commutator, or a damaged motor drive circuit (H-bridge MOSFET or relay) inside the ABS control module, preventing the pump motor from receiving drive current. 2) "Unable to stop running" — Indicates stuck motor drive relay contacts, failed control chip logic, or an abnormal feedback signal, causing the pump motor to run continuously when not required. This fault directly disables ABS, ESP, and TCS functions. In extreme cases, it affects brake pedal feel (hardening or abnormal pulsation). This is a Level 2 fault affecting driving safety.
C002192›
This fault code indicates the IPB (Integrated Power Brake) system detects pressure inside the brake booster chamber below the normal operating threshold. In models such as the Song PLUS DM-i, the IPB system generates brake assist pressure via an electric vacuum pump or direct motor drive and continuously monitors this pressure using a pressure sensor. The system triggers DTC C002192 when it detects assist pressure remaining below the target value (typically below -0.6bar or the set threshold range) for longer than the specified time (e.g., 500ms) and rules out sensor signal interference. This fault causes a hard brake pedal and increased braking distance. The system restricts the regenerative braking function and illuminates the ABS/ESC warning light. Extreme conditions may trigger Limp Home mode, severely compromising driving safety.
C002400›
DTC C002400 indicates the IPB (Integrated Electro-Hydraulic Braking) system detects an electrical fault in the brake pedal pressure feedback signal circuit. The IPB system uses the brake pedal travel sensor (or pressure sensor) to monitor the driver's braking intent in real time. This sensor typically mounts on the brake pedal mechanism or master cylinder input and provides an analog voltage or PWM signal to the IPB ECU. The ECU triggers this DTC when it detects an open circuit, a short to ground or power in the signal circuit, a signal voltage outside the calibrated range (e.g., 0.5-4.5V), or an abnormal signal drift rate. This fault limits or disables the brake assist function, deactivates the ESC/ABS system, and disables the Automatic Emergency Braking (AEB) function. The vehicle may enter mechanical backup braking mode, which significantly increases pedal effort and severely compromises driving safety.
C003108›
This DTC indicates the ABS control unit detects an abnormal or completely lost signal input while monitoring the left front wheel speed sensor. The wheel speed sensor (typically magnetic or Hall-effect) generates a pulse signal by monitoring the rotation of the tone ring on the half shaft or wheel hub. Systems such as ABS, ESC, and EPB rely on this signal to calculate wheel speed. The control unit sets C003108 when the signal voltage falls outside the threshold (<0.5V or >4.5V), the signal frequency is abnormal, or intermittent interruptions occur. This fault prevents accurate detection of the left front wheel speed. It triggers ABS failure, deactivates the ESC system, disables the automatic emergency braking system, and potentially affects the coordinated control of the energy recovery system. On pure electric models such as the E5, it also affects motor torque distribution and coasting energy recovery smoothness.
C003200›
This DTC indicates the IPB (Intelligent Integrated Brake Control Unit) detects an abnormal supply voltage to the left front wheel speed sensor. Specifically, the ECU detects the sensor supply circuit voltage (typically 12V battery voltage or 5V reference voltage) falls outside the normal threshold range (e.g., below 9V, above 16V, or deviating from the standard value by more than ±0.5V), or detects an open circuit, short to ground, or short to power in the supply circuit. This fault causes a missing or distorted left front wheel speed signal, triggering degradation protection in the ABS, ESC, and EPB systems. It affects regenerative braking efficiency, Automatic Emergency Braking (AEB), and vehicle stability control functions. In extreme cases, it may extend braking distance or cause the vehicle to pull to one side.
C003204›
DTC C003204 indicates an electrical fault in the left front wheel speed sensor (WSS) circuit within the BYD ABS system. This variable reluctance or Hall-effect sensor supplies the wheel speed signal to the ABS/ESC control unit. The control unit sets this code upon detecting an open circuit, short to ground, short to power, or abnormal signal interruption in the sensor circuit. In BYD new energy vehicles, this fault impairs normal ABS/ESP operation. It also limits regenerative braking, disables cruise control, disrupts four-wheel-drive torque distribution (if applicable), and may trigger a "Check braking system" warning. Because electric vehicles rely on wheel speed signals to calculate coasting energy recovery and estimate driving range, this fault reduces driving smoothness and causes inaccurate range displays. In severe cases, it triggers false ABS activation or complete ABS failure, compromising driving safety.
C003408›
DTC C003408 indicates the ABS control unit detects an abnormal right front wheel speed sensor (WSS) signal, specifically signal amplitude out of range, signal interruption, or excessive signal noise. On models such as the BYD E5, this sensor typically features a magnetic induction (passive inductive) design, generating a sine wave signal via the alternating magnetic field produced by the rotating tone ring (target wheel). If the signal voltage drops below the threshold (typically <0.1V), experiences interruption, or exhibits waveform distortion, the ABS/ESC system cannot accurately calculate the right front wheel angular speed. This disables anti-lock control, Electronic Brakeforce Distribution (EBD), the Traction Control System (TCS), and the energy recuperation braking coordination strategy. This classifies as a hard fault or an intermittent signal fault. The instrument cluster illuminates the ABS/ESC warning light, and some models limit energy recuperation strength and switch to a conventional hydraulic braking priority mode.
C003500›
DTC C003500 indicates the IPB (Intelligent Integrated Braking System) detected an abnormal supply voltage to the right front wheel speed sensor. On BYD e-Platform 3.0 and DM-i models, the wheel speed sensor typically uses a 12V DC supply (some earlier models use a 5V reference voltage). The IPB module identifies faults by monitoring the supply circuit voltage. The IPB sets this code when it detects a supply voltage below 9V (undervoltage), above 16V (overvoltage), or a complete open circuit (0V) lasting longer than the set threshold (typically 200ms). This fault causes a loss of the right front wheel speed signal. The IPB forcibly disables the ABS, ESC, EHB (Electro-Hydraulic Braking), and automatic emergency braking functions. The vehicle enters limp mode and multiple system warning lights illuminate on the instrument cluster, severely compromising driving safety.
C003504›
DTC C003504 indicates a right front wheel speed sensor (RF Wheel Speed Sensor) circuit or signal abnormality, specifically low sensor supply voltage, signal voltage out of range, or compromised circuit integrity. In the BYD ABS/ESP system, this fault prevents the control unit from obtaining an accurate right front wheel speed signal and triggers limp mode. Effects include: ABS function disabled, ESP deactivated, EBD malfunction, automatic emergency braking (AEB) function limited, regenerative braking efficiency reduced or disabled, and cruise control unavailable. This DTC is a hard fault. The control unit triggers this code upon continuously detecting the abnormality with the ignition switch in the ON position or while driving.
C003708›
C003708 is a UDS-compliant fault code; subtype '08' indicates Signal Invalid/Plausibility Failure. In the BYD E5 ABS/ESC system, this fault indicates the ABS ECU detects a persistent abnormality or intermittent interruption in the electrical signal from the left rear wheel speed sensor (RL Wheel Speed Sensor). Specific conditions include: signal amplitude outside the normal range (too high/too low), distorted signal waveform, excessive deviation from the reference model calculation, or logical inconsistency with the other three wheel speed signals (e.g., the left rear wheel speed reads significantly lower than the others during straight-line driving). In new energy vehicles, this fault also causes inaccurate torque calculation in the regenerative braking system (RBS), which may restrict regenerative braking functions. When this fault triggers, the system disables ABS and ESC functions, the ABS/ESC warning lamp illuminates on the instrument cluster, and the vehicle enters conventional hydraulic braking mode.
C003800›
DTC C003800 indicates the IPB (Intelligent Integrated Braking System) control unit detects the left rear wheel speed sensor supply voltage is outside the normal range (typically 12V or 5V, depending on the sensor model). This fault indicates an open circuit, short to ground, short to power, or excessive contact resistance in the power supply circuit between the IPB module and the left rear wheel speed sensor. This prevents the sensor from receiving a stable operating voltage. Because the wheel speed signal is a core parameter for ABS, ESC, TCS, AEB, and vehicle speed calculations, this fault causes these functions to fail or enter a degraded mode. On some hybrid models (such as DM-i), the abnormal vehicle speed signal may also restrict EV mode switching and permit only HEV mode driving for safety.
C003804›
This DTC indicates the ABS control unit (ESC module) detected abnormal electrical characteristics in the left rear wheel speed sensor circuit, including a signal line open circuit, short to ground, short to power, or intermittent connection. The ABS ECU fails to receive the square-wave speed signal from the left rear wheel, or the signal voltage falls outside the threshold range (normal static voltage approximately 11V; dynamic switching 0.5-11V). This fault triggers the ABS fail-safe mode, disabling or limiting the anti-lock braking, electronic stability control (ESC), autonomous emergency braking (AEB), and traction control (TCS) functions, and illuminates the ABS/ESC warning lamp on the instrument cluster. Due to the compact chassis layout and long wiring harness on pure electric models like the BYD E5, vehicle vibration rubbing the harness against sharp body edges, connector oxidation after water exposure, or poor internal contact in the power distribution box frequently cause this fault.
C003A08›
C003A08 indicates the ABS control unit detects an abnormal right rear wheel speed sensor (RR WSS) signal. Trigger conditions for this fault code include: complete loss of sensor signal (0 signal), signal amplitude below threshold, signal frequency mismatching the vehicle dynamics model (e.g., the other three wheels operate normally but the right rear signal changes abruptly), or electromagnetic interference causing signal noise. In BYD ABS systems, subtype 08 specifically denotes a signal plausibility fault or intermittent signal interruption, distinct from an open circuit (C003B) or power supply fault. This fault causes partial or complete failure of the ABS, EBD, ESC, TCS, and Automatic Emergency Braking (AEB) functions. The vehicle enters limp braking mode, retaining only basic hydraulic braking.
C003B00›
This DTC indicates the IPB (Intelligent Integrated Brake System) controller detects the right rear wheel speed sensor (WSS) supply voltage falls outside the normal threshold range (typically 4.5V-16V, depending on vehicle configuration). This is a hardwire circuit fault at the power supply level, not a signal transmission issue. The IPB triggers C003B00 upon detecting a short to ground (voltage too low/0V), a short to power (voltage too high/battery voltage), or high circuit resistance (unstable voltage) at the right rear wheel speed sensor power terminal. Because the wheel speed sensor provides a key input signal for the ABS, ESP, Automatic Emergency Braking (AEB), and Auto Hold systems, this fault causes a missing or distorted right rear wheel speed signal and triggers the brake system degraded mode. Some models also limit maximum vehicle speed or disable regenerative braking.
C003B04›
DTC C003B04 indicates the ABS control unit detects an electrical fault in the right rear wheel speed sensor signal circuit, including open circuit, short to ground, short to power, or abnormal signal. The wheel speed sensor (typically utilizing Hall effect or electromagnetic principles) serves as a key input component for the ABS/ESC system. It converts wheel speed into electrical signals and transmits them to the control unit to calculate slip ratio, vehicle speed, and travel direction. Triggering this DTC degrades or disables functions such as Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD), Electronic Stability Program (ESP), and Automatic Emergency Braking (AEB). The instrument cluster illuminates the ABS/ESC warning lamp to alert the driver. In models such as the BYD E5, the sensor typically integrates into the wheel hub assembly and connects to the ABS control unit via the floor wiring harness. The wiring routes through wear-prone areas like the chassis side member, frequently developing hidden faults after long-term use.
C004008›
DTC C004008 indicates the ABS/ESC control unit detected an abnormal Brake Pedal Switch signal. The Brake Pedal Switch typically contains primary and secondary contact sets (a normally open/normally closed combination) to provide hard-wired driver braking intent signals to the Vehicle Control Unit (VCU) and the ABS module. These signals directly affect brake light control, regenerative braking cancellation, Auto Hold logic, and vehicle power-up (Ready) permission. This DTC sets when the ABS module detects the switch signal voltage, logic combination (whether primary and secondary signals are mutually exclusive), or signal change rate exceeds calibrated thresholds. Potential causes include a single-circuit open, simultaneous dual-circuit short, signal desynchronization, or internal switch failure. A persistent fault causes abnormal regenerative braking, ESP function degradation, and brake lights stuck on or off. Extreme conditions trigger vehicle limp mode or prevent vehicle power-up.
C004601›
DTC C004601 indicates an abnormal brake master cylinder pressure sensor signal in the ESP (Electronic Stability Program) system. This sensor integrates into the ABS hydraulic modulator (pump unit) and monitors brake system hydraulic pressure in real time, providing key input signals for ESP, HDC (Hill Descent Control), and AEB (Automatic Emergency Braking). A pressure signal outside the normal range (such as an open circuit, short circuit, signal drift, or delayed response) triggers this fault code. This limits or disables the ESP function, affecting vehicle stability control, but basic braking usually remains unaffected. Clearing the code will not resolve this hardware-level fault.
C004900›
DTC C004900 indicates an abnormal brake fluid level detected by the IPB (Intelligent Integrated Braking System). The fluid level sensor installed in the brake master cylinder reservoir (typically a Hall-effect or float switch) triggers this fault. The IPB control unit records the fault when the brake fluid level remains continuously below the minimum mark (MIN) or the sensor signal voltage falls outside the calibrated range (normally 0.5V-4.5V, varying linearly with fluid level). This is a safety-related fault. When triggered, the system limits ESC, ABS, Automatic Emergency Braking (AEB), and energy recovery functions. Some models enter limp mode. Depending on the software version or specific repair scenario, this fault code may also correlate with an abnormal brake pedal position sensor (BPS) signal. The IPB system verifies brake system integrity by evaluating both the fluid level and pedal signals.
C004C04›
On BYD new energy vehicles (particularly the E5 and Song series), DTC C004C04 indicates a circuit fault in the Electronic Parking Brake (EPB) right rear wheel actuator, rather than an ESP switch fault as stated in the original documentation. Specifically, the EPB control unit detects an open circuit, short circuit, or abnormal resistance in the right rear parking motor circuit, preventing the motor from completing the clamp/release action. This fault triggers the system protection mechanism. It may cause the right rear wheel to lock mechanically, prevent the EPB from releasing automatically (failing to disengage when shifting into gear and applying the accelerator), and compromise vehicle launch and driving safety. Although the EPB and ESP (Electronic Stability Program) interact during brake management, this code specifically indicates a hardware or wiring fault in the parking brake actuator.
C006102›
DTC C006102 indicates the Intelligent Power Brake (IPB) system received a lateral acceleration (Ay) sensor signal outside the plausible range or with an abnormal status. This sensor typically integrates with the longitudinal acceleration (Ax) sensor and yaw rate sensor into a single inertial sensor module mounted in the center of the vehicle chassis or under a seat. It provides a key input signal for the Electronic Stability Control (ESC) system, Anti-lock Braking System (ABS), and electronic parking system. When this fault triggers, the IPB system cannot accurately obtain the vehicle's lateral dynamic parameters, limiting or disabling the body stability control function. This condition may also trigger a chain reaction fault in the electronic parking system, severely compromising vehicle stability and safety during cornering or emergency evasive maneuvers. The '02' suffix in the fault code indicates a signal plausibility error, meaning the signal value logically conflicts with the vehicle's actual condition or data from other sensors.
C006208›
DTC C006208 indicates the Electronic Stability Program (ESP) control unit detects an abnormal signal from the Longitudinal Acceleration Sensor (LAS). This sensor, typically integrated within the IPB (Intelligent Integrated Braking System) or ESP hydraulic modulator assembly, monitors the vehicle's longitudinal acceleration (G value) in real time. It provides a critical input signal for ESP vehicle stability control, TCS traction control, and brake force distribution. Fault conditions include signal circuit open or short, sensor signal out of range (±1.5g), signal drift, sensor self-test failure, or lost calibration data. When this fault occurs, the ESP system enters a degraded mode. Automatic Emergency Braking (AEB), Traction Control (TCS), and Electronic Brakeforce Distribution (EBD) functions may be limited or disabled. The ESP/ABS warning lights illuminate on the instrument cluster, severely compromising driving stability and braking safety.
C006108›
DTC C006108 indicates an abnormal signal from the lateral acceleration sensor (AY sensor) in the Electronic Stability Program (ESP) system. The ESP Hydraulic Electronic Control Unit (HECU) typically houses this sensor to monitor the vehicle’s lateral acceleration (lateral G-force) in real time. The sensor provides a key input for the ESP to calculate vehicle dynamic attitude, sideslip tendency, and yaw rate correction. The ECU triggers this fault upon detecting a sensor signal outside the calibrated range (e.g., 0.5-4.5V), excessive signal drift, intermittent interruptions, or logical inconsistencies with yaw rate sensor or wheel speed sensor data. This fault degrades or completely disables active safety functions such as ESP, ABS, and TCS, though the vehicle typically retains basic hydraulic braking. On the E5 model, the lateral acceleration sensor and HECU feature an integrated design. Do not replace the sensor separately; replace the complete HECU assembly.
C006164›
DTC C006164 indicates the IPB (Integrated Intelligent Braking System) detected an abnormal Lateral Acceleration Sensor (LAS) signal or a sensor fault. The LAS is a core sensor in the ESP/ESC vehicle stability control system. It monitors vehicle lateral acceleration (centrifugal acceleration) in real time, helping the ECU detect unstable conditions such as side slip, fishtailing, or understeer. This fault degrades or completely disables the ESC, ABS, TCS (Traction Control System), and Automatic Emergency Braking (AEB) functions. The vehicle enters Limp Mode, and the instrument cluster simultaneously illuminates the ABS and ESC warning lights. BYD’s new-generation IPB system typically integrates the lateral acceleration sensor into the Inertial Measurement Unit (IMU) inside the IPB assembly, rather than using a separate external sensor. Therefore, this fault usually indicates an internal hardware or communication link issue within the IPB assembly.
C006202›
DTC C006202 indicates the IPB (Intelligent Integrated Braking System) detected an abnormal longitudinal acceleration sensor signal. This sensor measures the vehicle’s longitudinal acceleration (deceleration) G-value. It provides a key input signal for the coordinated control of Electronic Stability Control (ESC), the Anti-lock Braking System (ABS), Automatic Emergency Braking (AEB), and the energy recovery system. BYD DMi models typically integrate this sensor within the IPB assembly or mount it on the chassis as an independent inertial sensor. A signal fault causes these safety systems to enter a degraded mode or fail, affecting driving stability, particularly during emergency braking and handling on slippery roads.
C006302›
DTC C006302 indicates the IPB (Intelligent Integrated Braking System) receives an abnormal yaw rate sensor signal. The ESP (Electronic Stability Program) system relies on the yaw rate sensor to detect the vehicle's real-time rotational angular velocity around the vertical axis (such as oversteer or understeer). This fault means the IPB module receives CAN bus message 0x222 with a yaw signal that falls outside the valid range, is missing, or contains a checksum error. This condition forces systems including the ESP, ABS, EPB (Electronic Parking Brake), and Automatic Emergency Braking into a degraded mode or complete failure, severely compromising vehicle dynamic stability control and driving safety.
C006308›
The yaw rate sensor (also known as the yaw angular velocity sensor) is the core inertial measurement unit of the ESP electronic stability system. It monitors the vehicle's rotational angular velocity around the vertical axis (Z-axis) in real time. DTC C006308 indicates the ABS/ESP control unit detects the sensor's analog or digital output signal continuously exceeds the valid threshold range (typically 0-5V or an abnormal CAN signal), or experiences an abnormal update frequency or checksum error. This fault prevents the ESP from accurately determining the deviation between the vehicle's actual attitude and the driver's steering intent, causing the system to exit the stability control function and trigger a multi-system degraded protection mode. In extreme cases, the vehicle loses electronic assistance during emergency obstacle avoidance or sideslipping on wet or slippery roads, posing a severe safety hazard.
C006382›
BYD's IPB (Integrated Brake Control System) defines DTC C006382 as a lateral acceleration sensor (G200) signal plausibility fault, rather than a simple yaw rate sensor fault. This sensor typically mounts beneath the center console or behind the center armrest. It continuously monitors lateral acceleration (in m/s² or G) during cornering or skidding, serving as a core input signal for the ESC (Electronic Stability Control) system to determine the vehicle's dynamic attitude. The IPB control unit deems the signal unreliable and triggers this DTC if the sensor output falls outside the plausible range (does not approach 0 when stationary), exhibits excessive drift, or if the sensor mounting reference plane deviates from the vehicle horizontal plane by more than 3°. Following this fault, active safety functions including ESC, ABS, and Automatic Emergency Braking (AEB) may degrade or fail completely. In extreme cases, the vehicle may lose stability control on curves or slippery surfaces, posing a severe safety risk.
C006A01›
This DTC indicates the IPB (Integrated Power Brake) or ESC (Electronic Stability Control) system detects an abnormal parameter configuration status for the yaw rate sensor. Specifically, the control unit cannot correctly identify the sensor identity type, range parameters, or installation direction configuration, causing the system to flag an "unknown sensor type" or "parameter configuration error". This typically occurs when failing to write parameters after replacing the IPB assembly, ESC module, or yaw rate sensor, or when the sensor hardware model does not match the software configuration. The fault degrades or disables functions including Electronic Stability Control (ESC), Anti-lock Braking System (ABS), and Automatic Emergency Braking (AEB), compromising driving safety in extreme cases.
C006A02›
DTC C006A02 indicates a functional failure or abnormal signal from the combined inertial sensor (typically an integrated yaw rate and lateral/longitudinal acceleration sensor) in the IPB (Intelligent Electro-Hydraulic Braking) system. This sensor typically mounts in the vehicle center tunnel (under the armrest) near the center of gravity. It acts as the core sensing component for the ESC (Electronic Stability Control), ABS (Anti-lock Braking System), TCS (Traction Control System), and AEB (Automatic Emergency Braking) systems. When this fault triggers, the IPB ECU cannot obtain accurate vehicle attitude, lateral acceleration, and yaw rate data, causing these active safety functions to degrade or fail completely. This failure risks a loss of vehicle stability control; therefore, the system classifies it as a Level 3 severe fault.
C006B00›
DTC C006B00 in the BYD IPB (Intelligent Integrated Brake) system indicates the Electronic Stability Program (ESP/ESC) activation time exceeds the designed safety threshold. This fault does not simply mean the system operated too long; it indicates the IPB control module detects vehicle stability control functions (including anti-skid, traction control, and yaw moment control) continuing to operate under non-essential conditions, or the system failing to exit the stability control state. This typically points to signal drift, calibration errors, or wiring faults in inertial measurement units, such as the yaw rate sensor and longitudinal/lateral acceleration sensors. These issues cause the IPB to misjudge the vehicle as continuously unstable. This fault triggers IPB system degradation and may limit or disable functions such as ABS, ESP, and Automatic Emergency Braking (AEB), severely compromising driving safety.
C007200›
C007200 is an advanced diagnostic trouble code in the BYD Integrated Power Brake (IPB) system. It indicates an abnormal thermal condition or pressure-temperature correlation in hydraulic brake circuit A (typically the front brake circuit). The system triggers this code based on a combined assessment of real-time master cylinder pressure sensor data, the hydraulic valve body temperature prediction model, and the braking frequency algorithm. The system records this fault when brake fluid temperature exceeds the preset threshold (typically caused by frequent braking, throttling heat generation from internal hydraulic leakage, or high ambient temperatures), or when the pressure sensor signal logically mismatches the temperature model. This fault may degrade ESP/ABS functions, cause abnormal brake pedal feel (soft or hard), and restrict regenerative braking. Severe cases trigger overheat protection and cut off power output.
C007204›
DTC C007204 indicates the standard solenoid valve (typically the inlet or outlet valve) inside the ABS/ESC Hydraulic Electronic Unit (HEU) triggered the overheat protection mechanism. The control unit detected the valve body temperature exceeded the safe threshold (typically >120°C) and entered protection mode to prevent valve spool binding or coil burnout. Root causes include: 1) Actual overheating (continuous heavy braking, brake drag, or increased movement resistance from degraded brake fluid); 2) False overheat detection (abnormal valve coil resistance, control unit temperature monitoring circuit failure, or software algorithm error). This fault limits or disables ABS/ESC functions, retaining only basic hydraulic braking. This severely compromises braking safety and requires immediate repair.
C007500›
DTC C007500 indicates an electrical fault or short circuit in Master Cylinder Position Sensor A within the IPB (Intelligent Power Brake) system. This sensor typically uses a Hall-effect or inductive principle and mounts near the brake master cylinder. It monitors master cylinder piston travel in real time, converting the driver's mechanical braking intent into an electrical signal (typically a 0.5-4.5V analog voltage) and transmitting it to the IPB ECU. The ECU uses this signal to calculate the required brake fluid pressure and controls the motor to build hydraulic pressure. The ECU sets this DTC when it detects the sensor signal voltage continuously exceeding the valid range (short to power >4.8V or short to ground <0.2V), or an abnormal logical relationship between the signal and pedal travel. Setting this DTC causes the IPB system to enter a degraded mode, disable brake energy recovery, retain only basic hydraulic braking, and illuminate the ABS/ESC warning light.
C00A800›
This DTC indicates the Integrated Inertial Sensor (IIS) in the ESP (Electronic Stability Program) system lacks initial calibration, or the calibration data is abnormal or invalid. The Integrated Inertial Sensor integrates a high-precision MEMS accelerometer and gyroscope to monitor the vehicle’s longitudinal acceleration, lateral acceleration, and yaw rate in real time. The ESP uses these core input signals for body stability control, anti-skid calculations, and Automatic Emergency Braking (AEB) decisions. The ECU sets this DTC when it detects a significant deviation between the sensor output and the expected reference, when the calibration data area checksum validation fails, or when the installation attitude angle exceeds the permitted tolerance. This condition forces the ESP system into a degraded mode, restricting or disabling functions such as the Anti-lock Braking System (ABS), Traction Control System (TCS), Vehicle Dynamics Control (VDC), and AUTOHOLD. In extreme cases, this compromises driving safety.
C012104›
DTC C012104 indicates the ABS/ESP electronic control unit (ECU) detected a fault in the solenoid valve relay control circuit. This relay resides inside the hydraulic control unit (HCU) and supplies stable operating power (typically 12V) to the inlet/outlet solenoid valve assembly. The ECU triggers this fault upon detecting an open or short in the relay coil circuit, or abnormal relay contact feedback voltage (such as output voltage dropping below the threshold after the relay energizes). This fault disables active safety functions relying on hydraulic regulation, such as ABS, EBD, ESP, and TCS. The vehicle retains only basic hydraulic braking capability. In models such as the BYD E5, the HCU integrates this relay. The relay is not serviceable separately; replace the complete assembly.
C019604›
This DTC indicates a functional fault in the Inertial Measurement Unit (IMU) integrated within the ESP (Electronic Stability Program) hydraulic modulator. This MEMS-based sensor assembly integrates a Yaw Rate Sensor and a Lateral G-Sensor. It monitors the vehicle's real-time rotational angular velocity around the vertical axis and lateral acceleration to provide critical vehicle dynamic attitude parameters for the ESP, TCS, HHC, and AEB systems. Sub-code '04' specifically indicates a signal circuit/range/performance fault or an internal self-test failure. Possible causes include: 1) Physical damage to the sensor hardware (internal silicon structure fracture or cracked solder joints); 2) Operating temperature outside the rated range (-40°C to +85°C); 3) Signal output exceeding valid thresholds (e.g., yaw rate ±75°/s or lateral acceleration ±1.5g); 4) ECU internal A/D converter or power management circuit fault. This fault causes complete failure of the vehicle stability control system. It creates a loss-of-control risk under extreme conditions (such as high-speed cornering or emergency obstacle avoidance) and may compromise the accuracy of the brake energy recovery strategy. This is a safety-critical fault requiring immediate repair.
C024501›
DTC C024501 indicates a general Wheel Speed Sensor Fault in the BYD ABS/ESP system. The ABS control unit (ECU) sets this code when it detects an abnormal or completely lost wheel speed signal from at least one wheel while the vehicle is moving. Specifically, the ECU triggers this DTC if the vehicle speed exceeds 2 km/h and the ECU fails to receive a pulse signal from a wheel speed sensor, or if the speed difference between the affected wheel and the opposite wheel on the same axle (or the reference vehicle speed) exceeds the set threshold (typically 6%) for longer than the specified time (typically 500 ms). This fault forces the Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD), Electronic Stability Program (ESP), Traction Control System (TCS), Auto Hold, and energy recovery systems into a degraded or inoperative mode. This severely compromises braking safety and driving stability. This DTC represents a circuit or signal fault and does not involve a mechanical actuator. However, mechanical or electrical issues with the sensor body, wiring harness, connector, or signal tone ring can cause the fault.
C040008›
C040008 is a UDS diagnostic protocol chassis system fault code indicating an abnormal communication signal between the EPB (Electronic Parking Brake) control module and the ABS/ESC module. This fault indicates the ABS system received an EPB status signal (e.g., parking motor position, clamping force, switch status, or system ready status) with a validity error, checksum error, signal timeout, or out-of-range value. This fault may cause AUTO HOLD function failure, abnormal Hill Hold Control (HHC) operation, or failure of the electronic parking brake to apply or release. Extreme cases compromise driving safety.
C046008›
DTC C046008 indicates an unreliable or incorrect SAS (Steering Angle Sensor) signal value in the EPS (Electric Power Steering) system 0x11F message. Although originally classified under the ABS/braking system, modern vehicle architectures route the SAS signal via the CAN bus to both the ESP (Electronic Stability Program) and the EPS. The control unit sets this fault when it detects the steering angle sensor signal exceeds the plausible range, exhibits abnormal jumps, experiences a sampling timeout, or fails the logical correlation check with the wheel speed sensor signals (as related code C052801 indicates). This fault limits ESP functionality, causes abnormal steering assistance, or disables the automatic emergency braking system, severely impacting driving stability.
C050200›
This DTC indicates the IPB (Intelligent Integrated Braking System) control unit detects an abnormally low-resistance connection between the left front wheel speed sensor (WSS) power supply circuit (typically a 12V DC supply) and body ground (GND), indicating a short to ground. The wheel speed sensor uses a two-wire design (multiplexed power/signal or independent power and ground). When the power supply circuit shorts to ground, the sensor fails to receive normal operating voltage. This causes a complete loss of the left front wheel speed signal and prevents the IPB from monitoring the left front wheel speed. This fault directly degrades or completely disables systems including the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Traction Control System (TCS), Automatic Emergency Braking (AEB), and Electronic Parking Brake (EPB). The vehicle may enter a safety protection mode (limp mode) and brake pedal feel may change, severely compromising driving safety.
C050300›
DTC C050300 indicates a short to battery positive (B+) in the left front wheel speed sensor (WSS) power supply circuit. Normally, the IPB (Integrated Power Brake) supplies 5V or 12V to the wheel speed sensor (depending on sensor type). A "short to battery" condition means the power supply line shorts to a vehicle constant power circuit, or the internal sensor power terminal breaks down to the signal or ground terminal. This causes the control unit to detect an abnormally high voltage (approximately 12V battery voltage). This prevents the IPB from correctly reading the left front wheel speed signal, triggers the safety protection mechanisms of systems such as ABS, ESP, and Automatic Emergency Braking, and disables the related functions.
C050400›
DTC C050400 indicates the IPB (Intelligent Integrated Braking System) control unit detects an "indirect uncertainty" (plausibility fault) in the left front wheel speed sensor signal. This is not a simple sensor open or short circuit. Instead, the control unit algorithm identifies a logical inconsistency between the left front wheel speed signal and the vehicle's actual motion state, the speeds of the other three wheels, and the longitudinal/lateral acceleration sensor data. Symptoms include signal spikes, an abnormal fixed value (such as a constant 1845 km/h), a signal rate of change exceeding physical limits, or intermittent signal loss within specific vehicle speed ranges (usually >60 km/h). This fault triggers degraded protection modes in systems including ABS, ESP, and automatic emergency braking, severely affecting vehicle dynamic stability control.
C050576›
This DTC indicates the IPB (Integrated Intelligent Braking System) detects a correlation plausibility fault in the left front wheel speed sensor signal. Specifically, the frequency or amplitude of the sensor pulse signal logically conflicts with the actual vehicle motion state, the other three wheel speed signals, or the longitudinal acceleration sensor data, failing the system plausibility check algorithm. This fault typically indicates intermittent sensor signal interruption, electromagnetic interference, magnetic ring (magnetic encoder) demagnetization, or out-of-tolerance mechanical installation clearance. These conditions prevent the ABS/ESC from accurately identifying the actual left front wheel speed, triggering the ABS warning light and ESC OFF light, and degrading the automatic emergency braking system.
C050600›
DTC C050600 indicates the IPB (Intelligent Integrated Braking System) detects an electrical circuit fault in the right front wheel speed sensor (WSS). This is a circuit integrity fault. The ECU detects sensor signal voltage outside the normal threshold (typically 0.1V-4.9V), a short to power or ground, an open circuit, or signal interference. The BYD IPB system uses a two-wire Hall effect or magnetoelectric wheel speed sensor. The ECU continuously monitors the sensor supply current and signal waveform. If the right front wheel speed signal is lost or distorted, the system disables functions relying on wheel speed data, including ABS, EBD, TCS, ESC, and AEB. The vehicle retains basic hydraulic braking capability. This fault illuminates multiple instrument cluster warning lights (ABS/ESC/AEB) and triggers Limp Home mode, which limits power output or disables energy recovery.
C050800›
DTC C050800 indicates an abnormal short circuit between the right front wheel speed sensor power supply circuit (typically a 12V or 5V reference voltage) and body ground (GND). In the BYD IPB (Integrated Power Brake) architecture, the active wheel speed sensors (Hall-effect or magnetoelectric) require a stable operating voltage from the ECU. When the power supply line shorts to ground, the IPB module detects an abnormal current increase or a voltage drop to near 0V and triggers the fault protection mechanism. This fault causes the loss of the right front wheel speed signal, disabling or degrading functions such as the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Traction Control System (TCS), and Automatic Emergency Braking (AEB). This hard fault severely impacts driving safety.
C050900›
This DTC indicates a short circuit between the 12V power supply wire and the signal output circuit of the right front (FR) wheel speed sensor, or a direct short from the signal wire to battery positive (B+). In the BYD IPB (Intelligent Integrated Braking System) architecture, the wheel speed sensor is typically a Hall-effect type. Under normal operation, the supply voltage is 12V, and the signal wire outputs a 0.5-4.5V pulse voltage. When the signal wire shorts to the 12V supply, the IPB control unit receives a continuous high-level signal and cannot identify wheel speed pulses. This causes the system to lose the right front wheel speed data or display an abnormal fixed value. This condition triggers the safety protection mechanisms of systems including ABS, ESP, and EHB (Electro-Hydraulic Braking), causing brake assist functions to degrade or fail. Multiple warning lights illuminate on the instrument cluster, severely compromising driving safety.
C050A00›
DTC C050A00 indicates the IPB (Intelligent Integrated Braking System) ECU detects the air gap between the right front wheel speed sensor (WSS) and the signal tone ring exceeds the calibrated tolerance range (typically 0.3-1.2mm), or the sensor signal amplitude/phase exhibits intermittent erratic characteristics. This is a plausibility fault, distinct from a direct short or open circuit. The IPB system uses an active Hall-effect wheel speed sensor highly sensitive to the installation air gap. An excessive gap attenuates the signal, while an insufficient gap causes the sensor head to rub against the tone ring. The ECU sets this fault when algorithmic compensation cannot verify wheel speed signal reliability. This fault degrades or disables ABS, ESP, TCS, and Automatic Emergency Braking (AEB) functions. In severe cases, it illuminates the brake system warning lamp continuously.
C050B76›
DTC C050B76 indicates the IPB (Intelligent Integrated Braking System) detects a correlation fault in the right front wheel speed sensor signal. This fault does not indicate a simple signal loss (open circuit). Instead, the sensor pulse signal output logically mismatches actual vehicle dynamics (e.g., other wheel speeds, vehicle speed, acceleration, yaw rate), or the signal characteristics (frequency, amplitude, duty cycle) exceed calibrated thresholds. The IPB algorithm compares the correlation of all four wheel speed sensors. The system sets this code when the right front signal differs excessively from the other wheel speeds, exhibits erratic signal jumps, or experiences an intermittent fault in the sensor power supply or ground circuit. This fault directly affects the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Automatic Emergency Braking (AEB), and energy recovery functions. It may increase braking distance or cause abnormal brake pedal feel.
C050C00›
DTC C050C00 indicates the IPB (Integrated Intelligent Brake Control System) detects an electrical fault in the left rear wheel speed sensor (WSS) wiring harness, including an open circuit, short circuit, or short to ground or power. This sensor, typically a Hall-effect or magnetoelectric type, converts wheel speed into an electrical signal and transmits it to the IPB module. The IPB module uses this signal for precise control of systems including ABS, ESC, TCS, EPB, and Automatic Emergency Braking (AEB). A wiring harness fault prevents the IPB from obtaining left rear wheel speed data and triggers a system degraded mode (ABS/ESC functions limited or disabled). In extreme cases, this fault can affect brake force distribution, cause abnormal parking brake operation, or trigger speed-limiting protection, posing a driving safety risk.
C050E00›
DTC C050E00 indicates the IPB (Intelligent Integrated Braking System) or ABS module detects an abnormal short circuit to vehicle ground (GND) in the left rear wheel speed sensor (WSS) power supply circuit (typically the 12V supply line). This supply circuit provides the operating voltage for the Hall-effect or magnetic wheel speed sensor. When a short to ground occurs, the power driver circuit inside the ABS module detects overcurrent or a voltage drop to nearly 0V, triggering the protection mechanism and storing the fault code. This fault causes a missing or abnormal left rear wheel speed signal, forcing active safety functions such as ABS, ESC, TCS, and Automatic Emergency Braking (AEB) into fail-safe mode (conventional braking). The instrument cluster illuminates multiple warning lamps, including ABS, ESC, and EBD. This severely compromises driving safety and creates a risk of wheel lock-up, especially on slippery roads or during emergency braking.
C051000›
DTC C051000 indicates the IPB (Integrated Intelligent Braking System) detected an abnormally low-resistance path between the left rear wheel speed sensor power supply circuit (typically a 5V or 12V reference voltage) and the vehicle main power supply (B+, battery voltage). In automotive electronic diagnostics, "Short to Battery" means the signal wire or power supply wire shorted to the positive 12V power supply. This fault causes the sensor supply voltage to rise abnormally above the rated 5V/12V to the 13-14V battery voltage range, triggering the overvoltage protection mechanism in the IPB control unit. Because the wheel speed signal is a core input parameter for the ABS, ESC, EBD, and Autonomous Emergency Braking (AEB) systems, this fault causes these safety systems to enter a degraded mode or fail completely, posing a severe driving safety hazard. Potential causes include physical damage to the wiring harness, electronic component breakdown inside the sensor, water ingress and corrosion in the connector, or a power management chip failure inside the IPB control unit.
C051176›
The BYD IPB (Intelligent Integrated Braking System) defines DTC C051176 as "Incorrect Installation Direction of Left Rear Wheel Speed Sensor". This fault does not indicate a simple open or short circuit. Instead, the magnetic pole direction of the Hall-effect wheel speed sensor mismatches the relative position of the tone ring, reversing the output square-wave signal phase or generating an abnormal duty cycle. The IPB control unit triggers this code upon detecting unexpected rising and falling edge timing in the signal waveform, or upon identifying a logical conflict between the left rear wheel speed signal and the other three wheels during vehicle speed calculation. This fault directly disables or falsely triggers the Anti-lock Braking System (ABS), Electronic Stability Program (ESP), Automatic Emergency Braking (AEB), and tire pressure monitoring system (calculated via wheel speed differentials), severely compromising driving safety.
C051200›
DTC C051200 indicates the IPB (Intelligent Integrated Braking System) detected a persistent or intermittent electrical fault in the right rear wheel speed sensor (RR WSS) circuit. This fault occurs when the IPB module fails to receive a valid wheel speed signal within the specified time, or detects signal voltage/resistance outside the threshold range (typically an open circuit, short to ground, short to power, or signal interference). On vehicles equipped with the IPB (One-box) integrated braking system, such as the BYD Song PLUS DM-i, this fault disables or limits the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Automatic Emergency Braking (AEB), Hill Hold Control (HHC), and Adaptive Cruise Control (ACC) functions. Additionally, because New Energy Vehicles (NEVs) rely on wheel speed signals to calculate regenerative braking torque, this fault may cause abnormal energy recovery, inaccurate driving range display, and force the drive system into protection mode.
C051400›
This DTC indicates the IPB (Intelligent Integrated Braking System) detects an abnormally low-resistance connection between the right rear wheel speed sensor power supply circuit (typically a 12V or 5V reference voltage) and body ground (GND), constituting a short to ground. In the BYD IPB system, the wheel speed sensor is a two-wire active Hall sensor. The ECU supplies operating voltage to the sensor via the power supply line. A short to ground on the power supply line causes: 1) complete loss of the right rear wheel speed signal; 2) the IPB system to trigger limp mode, automatically disabling the dynamic functions of the ABS, ESC, Automatic Emergency Braking (AEB), and Electronic Parking Brake (EPB); 3) potential damage to the internal IPB driver circuit if the short-circuit current is excessive. This is a hard-wire circuit fault, not signal interference or performance degradation. Repair the fault immediately to prevent braking system failure.
C053D00›
This fault code indicates the IPB (Intelligent Integrated Braking System) detects the hydraulic pressure value from the brake master cylinder pressure sensor falls outside the system-calibrated normal threshold range (too high or too low). The IPB system monitors the driver’s braking intent and hydraulic circuit status in real time via the master cylinder pressure sensor. The system logs a pressure out-of-range fault if the pressure signal voltage falls outside the valid 0.5-4.5V range, or if the pressure value mismatches the pedal travel and wheel cylinder pressure logic. This fault triggers a degraded protection mode, which may limit ABS/ESC functions, disable automatic emergency braking, or cause abnormal brake pedal feel, severely compromising driving safety.
C051500›
DTC C051500 indicates the IPB (Intelligent Integrated Braking System) detected a short circuit to battery positive (B+) in the right rear wheel speed sensor power supply circuit. This fault occurs when abnormal electrical continuity develops between the sensor power line (typically a 12V supply) and the vehicle constant power supply or the IPB internal power output stage, causing an abnormal voltage increase or current overload. The IPB control unit monitors the supply circuit voltage and current characteristics. Upon detecting a short circuit, it triggers a protection mechanism and cuts power to the circuit to prevent hardware damage. This fault causes the loss of the right rear wheel speed signal, disabling or degrading ABS, ESP, TCS, EPB, and Automatic Emergency Braking (AEB) functions, which severely compromises driving safety. The '00' suffix in the DTC typically indicates an active, hard fault (non-intermittent).
C051600›
DTC C051600 indicates the IPB (Intelligent Integrated Braking System) detects an intermittent abnormality or insufficient plausibility in the right rear wheel speed sensor signal. Unlike a direct open or short circuit fault, 'indirect uncertainty' means the sensor still returns a signal, but under specific operating conditions (such as a specific vehicle speed range, steering maneuver, or road input), the signal spikes, drifts, or illogically contrasts with the other wheel signals. The IPB system algorithm compares the four-wheel speed differential, longitudinal acceleration, and yaw rate signals. The system triggers this fault when the right rear wheel speed signal duration or amplitude exceeds the plausible confidence interval but has not yet reached the hard fault threshold. This condition typically indicates dynamic sensor-to-tone ring gap variation, electromagnetic signal interference, or an intermittent voltage drop in the sensor power supply or ground, which can cause ABS/ESC function degradation or false activation.
C051776›
The IPB (Intelligent Integrated Braking System) or ESC (Electronic Stability Control System) triggers this DTC. It indicates a wrong installation direction for the right rear wheel speed sensor. The sensor uses the Hall effect principle; its internal magnetic poles have a specific bias direction to identify the tone ring rotational direction. Installing the sensor opposite to the calibrated direction, or swapping the left and right sensors, produces an output signal polarity opposite to ECU expectations. This prevents the system from correctly interpreting the wheel speed signal. This condition degrades or disables functions such as ABS, ESP, Auto Hold, and Automatic Emergency Braking, representing a brake safety-related functional fault.
C051D01›
DTC C051D01 indicates an abnormal calibration status of the inertial measurement unit (IMU) inside the IPB (Integrated Power Brake). Specifically, the yaw rate sensor or longitudinal acceleration sensor reference data is lost, offset, or invalid. Integrated inside the IPB control module, this sensor monitors the vehicle’s rotational yaw rate about the vertical axis and its longitudinal acceleration in real time. It provides the core input signal the ESP electronic stability control system uses to calculate vehicle dynamic attitude. The IPB sets this code when it detects the sensor output deviates from the expected calibration reference beyond the threshold, or when it loses the stored calibration parameters. This limits ESP functionality or triggers limp mode; however, normal hydraulic braking usually remains unaffected.
C052801›
DTC C052801 indicates the Steering Angle Sensor (SAS) in the Intelligent Integrated Braking System (IPB) detects a steering angle value exceeding the valid system-calibrated range (typically ±720° or ±1440°, depending on vehicle calibration), or the sensor output signal voltage falls outside the normal 0.5-4.5V range. The Electronic Stability Control (ESC) system uses this key input sensor to determine the match between the driver's steering intent and the vehicle's actual yaw rate. When the steering angle value exceeds this range, advanced driver assistance functions including ESC, ABS, Automatic Emergency Braking (AEB), and Lane Keeping may enter a degraded mode or fail completely, severely compromising vehicle handling stability. Potential causes include a damaged sensor, an open circuit in the steering wheel clock spring, a Steering Column Control Module (SCCM) communication fault, an abnormal IPB internal signal processing circuit, or a missing SAS zero-point calibration following chassis repairs.
C052901›
DTC C052901 indicates a communication interruption or loss of data validity between the IPB (Intelligent Integrated Braking System) control unit and the Steering Angle Sensor (SAS). The steering angle sensor mounts on the steering column and transmits steering wheel angle, rotational speed, and direction information in real time to the IPB, VCU, ADAS, and other modules via the CAN bus. It provides the core input signal for the Electronic Stability Control (ESC), automatic parking, lane keeping, and Autonomous Emergency Braking (AEB) systems. The IPB triggers this fault when it fails to receive a valid steering angle data frame within 500 ms, or detects a sensor response timeout or checksum error. The vehicle then enters a degraded mode: ESC function is limited or disabled, skid control fails, and automatic parking is unavailable. Extreme cases may alter brake assist characteristics, but the system retains basic hydraulic braking.
C053B00›
DTC C053B00 indicates an open circuit or abnormal voltage in the ABS solenoid valve power supply circuit inside the IPB (Intelligent Integrated Braking) module. This fault means the ECU detects the power supply line voltage to the ABS hydraulic modulator solenoid valve falls outside the normal range (typically below 9V or above 16V) or has an open circuit. Because the IPB system integrates ABS, ESP, EHB (Electro-Hydraulic Braking), and other functions, an abnormal solenoid valve power supply causes safety functions such as anti-lock braking and vehicle stability control to fail or degrade. The system then enters fail-safe mode. External power supply circuit issues (fuses, wiring harnesses, connectors) or a fault in the IPB internal power management circuit can cause this fault. Repair the system immediately to ensure braking system reliability.
C053C00›
DTC C053C00 indicates the IPB (Intelligent Integrated Brake) system detects one or more wheel speed sensor input signals outside the plausible physical range. Specific conditions include: the sensor reports an equivalent vehicle speed exceeding the theoretical maximum vehicle speed (e.g., a frequency corresponding to over 250 km/h); the signal frequency or amplitude exceeds the ECU calibration threshold; or the four-wheel speed logic mismatches (e.g., one wheel speed reads abnormally higher than the others). This fault triggers the IPB safety protection mechanism, disables functions including ABS, ESC, and Automatic Emergency Braking, and forces the system into degraded mode.
C053C76›
DTC C053C76 indicates the IPB (Intelligent Integrated Braking System) detects a wheel speed sensor output signal exceeding the system's defined logical range. This fault is a signal anomaly that may manifest as: 1) Signal frequency/amplitude exceeding physical limits (e.g., vehicle speed above 300 km/h or below 0 with signs of movement); 2) Abnormal signal transition rate (e.g., instantaneous drop from 100 km/h to 0); 3) Signal distortion caused by sensor output noise interference. This fault limits or disables safety functions including ABS, ESC, and automatic emergency braking. The IPB system enters degraded protection mode and illuminates multiple warning lights on the instrument cluster.
C053E00›
DTC C053E00 indicates a short to ground in the signal circuit of IPB (Intelligent Integrated Braking System) master cylinder pressure sensor 1. This sensor monitors brake master cylinder hydraulic pressure in real time and serves as the core feedback component of the brake-by-wire system. The ECU uses this signal to calculate brake assist demand, trigger energy recovery, and control ABS/ESC intervention timing. The ECU sets this fault when it detects the sensor signal voltage remaining continuously below the threshold (typically <0.5 V, normal range 0.5–4.5 V) or an abnormal drop in signal wire resistance to ground. This fault causes abnormal brake pedal feel (too hard or too soft), degrades energy recovery, and forces the ESC/ABS system into a degraded mode (illuminating multiple instrument cluster warning lights). Extreme cases may trigger limp-home mode (speed-limited driving).
C053F00›
DTC C053F00 indicates an electrical circuit fault in Primary Pressure Sensor 1 within the IPB (Intelligent Integrated Braking System, One-Box brake-by-wire unit). Specifically, the signal circuit, 5V supply circuit, or ground circuit has a short to ground, short to power, or open circuit. This sensor is a core input component of the brake-by-wire system. It monitors brake master cylinder hydraulic pressure or pedal simulator pressure in real time, providing critical data for brake assist, energy recovery, ESC vehicle stability, and AEB automatic emergency braking. When this fault occurs, the IPB immediately enters limp-home mode, potentially causing a loss of brake assist, a hard brake pedal, and complete deactivation of ABS and ESC functions. This severe fault compromises driving safety.
C054100›
DTC C054100 indicates the analog voltage signal from the second pressure sensor (typically the accumulator pressure sensor or master cylinder pressure monitoring sensor) inside the IPB (Intelligent Power Brake) module exceeds the ECU-calibrated upper threshold (typically >4.8V or a corresponding pressure exceeding the system safety limit, such as >22MPa). In the Bosch IPB system used by BYD, this sensor uses the piezoresistive effect to convert hydraulic pressure into a 0.5-4.5V linear voltage signal. The ECU logs an "Out of Range High" fault when it detects this signal voltage remains above the valid physical range over multiple consecutive drive cycles (i.e., the sensor reports an excessively high pressure regardless of actual braking conditions). This fault triggers the IPB system to enter a safety degradation mode: it disables regenerative braking, limits ESC functions, maintains basic hydraulic brake assist, and illuminates the ABS/ESC warning lamps. If Sensor 2 monitors accumulator pressure, sustained high pressure may prevent the motor pump from starting or cause the pressure relief valve to remain open continuously, affecting brake pedal feel and response speed.
C054200›
DTC C054200 indicates an electrical signal fault in Pressure Sensor 2 within the IPB (Integrated Power Brake). This sensor typically provides the master cylinder pressure sensor secondary signal or monitors wheel cylinder pressure. The sensor transmits real-time brake pressure data to the IPB-ECU using a 0.5-4.5V analog voltage signal or a PWM digital signal. The ECU logs a short circuit (to ground or power) or an open circuit if the sensor signal voltage remains outside the valid threshold (typically below 0.25V or above 4.75V) for over 200ms. As the BYD IPB utilizes a Brake-by-Wire architecture, the pressure sensor signal serves as a key parameter for calculating brake force distribution, triggering ABS/ESC intervention, and coordinating electro-hydraulic braking with energy recovery. This fault triggers the IPB fail-safe mode, disabling ESC, AEB, Auto Hold, and brake energy recovery. The system retains only basic hydraulic brake assist, increasing the risk of extended braking distances.
C054300›
DTC C054300 indicates an abnormal electrical signal from Pressure Sensor 2 in the IPB (Intelligent Power Brake) electro-hydraulic module, specifically a short to power, short to ground, or open circuit in the signal circuit. This sensor monitors brake master cylinder pressure (or wheel cylinder pressure channel 2) and provides a key input signal for ESC (Electronic Stability Control) and brake assist functions. The ECU logs a hardware-level fault when it detects the sensor voltage signal falling outside the calibrated range (typically below 0.3V or above 4.7V, depending on the 5V reference voltage division logic). This fault forces the IPB into a degraded mode, disabling ESC/ESP and Automatic Emergency Braking (AEB) functions. The system may trigger limp mode (reducing brake assist). In extreme cases, the brake pedal hardens or braking distance increases, posing a serious safety hazard.
C055000›
DTC C055000 indicates an internal self-check fault in the ABS electronic control unit (ECU). Specifically, the control module integrated inside the ABS hydraulic modulator assembly detects a hardware or basic software abnormality. This constitutes a 'core-level' ABS system fault, indicating the ECU cannot execute normal anti-lock braking control logic. When triggered, the ABS system forces Fail-Safe Mode. This disables anti-lock braking, EBD (Electronic Brakeforce Distribution), and ESC (Electronic Stability Control) functions, retaining only conventional hydraulic braking. The instrument cluster illuminates the ABS warning light, ESC warning light, and brake system warning light. Some models also display the text prompt 'Please check brake system'. This DTC differs fundamentally from wheel speed sensor signal faults (such as the C003 series). The latter represents an 'input signal abnormality', whereas C055000 represents a 'control unit internal abnormality', involving significantly higher repair complexity and cost.
C055164›
DTC C055164 indicates the IPB (Integrated Power Brake) detects a fault in the Longitudinal Acceleration Sensor signal circuit. This sensor monitors longitudinal acceleration (braking deceleration/driving acceleration) and provides key vehicle dynamic parameters to the ESC (Electronic Stability Control), ABS (Anti-lock Braking System), AEB (Autonomous Emergency Braking), and energy recovery systems. When the fault triggers, the longitudinal acceleration signal status bit the IPB receives via CAN message 0x223 indicates an error (such as invalid signal, checksum error, or timeout), preventing the system from accurately determining the vehicle motion state. In severe cases, ESC, ABS, and AEB functions may enter a degraded mode or fail completely. The instrument cluster illuminates multiple brake system warning lamps, and extreme conditions compromise vehicle braking safety and stability control.
C055500›
This DTC indicates the IPB (Intelligent Integrated Braking System) control module detects a mismatch between the front left wheel speed sensor hardware identifier (HW ID) or signal characteristics and the vehicle configuration parameters (EPC/calibration data). Specifically, when reading the wheel speed sensor ID code, resistance characteristics, or signal waveform parameters via the LIN bus or dedicated wiring harness, the IPB module detects a deviation between the actual characteristic values and the expected theoretical values. This typically occurs when installing non-genuine parts, failing to reconfigure the system after a software upgrade, or when strong electromagnetic interference distorts the sensor signal characteristics. This fault limits or disables the ABS, ESC, EBD (Electronic Brakeforce Distribution), and Automatic Emergency Braking (AEB) functions, severely impacting the vehicle's active safety performance, but does not directly cause mechanical brake failure.
C055F92›
DTC C055F92 indicates an IPB (Integrated Power Brake) hydraulic subsystem performance fault. This DTC indicates the IPB control unit detects abnormal hydraulic circuit pressure, excessive pressure build-up time, insufficient pressure holding capability, or abnormal hydraulic pump motor operation. The IPB system integrates electric vacuum assist, ESP electronic stability control, and ABS anti-lock braking functions. This fault may reduce brake assist, harden the brake pedal, restrict or disable active safety functions (AEB/ACC), or in extreme cases, trigger the brake system downgrade protection mode. The fault suffix '92' indicates a hydraulic circuit performance deviation or intermittent operating abnormality rather than a complete failure.
C055600›
DTC C055600 indicates the IPB (Intelligent Integrated Braking System) control module detects the hardware model or electrical characteristics of the right front wheel speed sensor do not match the system calibration parameters. This is a configuration/calibration fault, not a simple signal fault. By monitoring the sensor resistance, signal voltage range, pulse characteristics, or digital communication protocol, the IPB system detects the installed sensor does not match the vehicle configuration code (VIN-corresponding calibration data). This typically occurs after installing non-genuine parts, installing a sensor from another vehicle model, or if the sensor does not match the wheel hub bearing assembly (some BYD models separate the magnetic encoder bearing from the sensor). When this fault triggers, the IPB enters degraded mode, disables ABS, ESC, Automatic Emergency Braking (AEB), and energy recovery functions, retaining only basic hydraulic braking.
C055700›
DTC C055700 indicates the IPB (Intelligent Integrated Braking System) detects the left rear wheel speed sensor electrical characteristics, signal pulse count, or communication protocol do not match system calibration parameters during self-check or signal monitoring. This fault is not a simple signal loss or short circuit; rather, the system identifies an abnormal sensor "identity". Possible causes include installing a non-genuine wheel speed sensor with incorrect specifications (mismatched resistance, pole count, or Hall element type), an abnormal match between the sensor and the tone ring (magnetic ring), or incorrect IPB control module software configuration (such as flashing configuration data from another vehicle model). This fault directly limits or completely disables functions relying on accurate wheel speed signals, including ABS, ESC, and EPB. In extreme cases, it causes wheel lock-up or skidding during emergency braking, making it a critical fault affecting driving safety.
C055800›
DTC C055800 indicates the IPB (Integrated Intelligent Braking System) control unit detects a mismatch between the digital signal protocol from the right rear wheel speed sensor (WSS) and the system preset standard. Specifically, the sensor PWM (pulse-width modulation) or square-wave signal exceeds calibrated thresholds for waveform characteristics, duty cycle, frequency range, or voltage amplitude, preventing the control unit from correctly interpreting wheel speed data. Unlike a simple signal loss (open circuit), this protocol-level communication mismatch indicates an incompatible sensor hardware version, signal distortion, or EMC interference. When this fault triggers, wheel speed-dependent systems (ABS, ESC, TCS) enter a degraded mode. On some models, the fault disables the automatic emergency braking system or limits vehicle speed.
C057900›
DTC C057900 indicates the IPB (Integrated Power Brake) electro-hydraulic control module detected a short to ground in the brake booster motor temperature sensor signal circuit. Typically integrated inside the electro-hydraulic brake booster, this temperature sensor uses a negative temperature coefficient (NTC) thermistor to monitor the booster motor operating temperature in real time and prevent overheating damage. The ECU logs a short to ground fault when the sensor signal voltage remains below the calibrated threshold (typically <0.5V) for longer than the set time (e.g., 200ms). This fault triggers the IPB system to enter a degraded safety mode, which may reduce or eliminate brake assist (hard brake pedal), disable the energy recovery system, restrict ABS/ESC functions, and illuminate multiple brake system warning lights. Continued driving under extreme operating conditions may cause a complete loss of brake assist, posing a serious safety risk. Workshop practice on certain vehicle models indicates this DTC may also involve a short to ground in the brake switch signal circuit.
C055F00›
DTC C055F00 indicates the IPB (Intelligent Integrated Brake System) detects a hydraulic circuit abnormality. The IPB is BYD’s electro-hydraulic integrated braking system (One-Box architecture), integrating brake boost, ESP, ABS, and EPB functions. This fault occurs when, during a self-check or braking request, the system detects the deviation between the master cylinder pressure sensor feedback and the target pressure exceeds the limit, the hydraulic pump fails to build the required pressure within the specified time, or solenoid valve actuation feedback is abnormal. Possible causes include hydraulic pump motor failure, pressure sensor drift, a sticking solenoid valve, brake fluid leakage/air lock, or an internal control unit sampling circuit fault. When this fault occurs, the system may enter Limp Home mode, limiting brake boost or switching to mechanical backup mode, severely affecting braking performance.
C056364›
DTC C056364 indicates the ABS control module inside the IPB (Intelligent Integrated Brake System) detects an internal operating fault. The IPB is BYD's one-box brake-by-wire solution (such as the Bosch IPB or BYD in-house IPB), integrating ABS, ESC, regenerative braking, automatic emergency braking, and other functions. Sub-code 64 usually indicates a control module internal self-test failure, involving a main control chip (MCU) fault, abnormal power supply voltage monitoring, internal memory (Flash/RAM) errors, a solenoid valve drive circuit fault, or a watchdog reset. This fault causes ABS, ESC, TCS, AEB, and other functions to fail or enter degraded mode. The instrument cluster illuminates the ABS and ESC warning lights, and the vehicle may limit power output. The vehicle usually retains basic hydraulic braking (the brake pedal may feel hard).
C056B00›
DTC C056B00 indicates an abnormal signal from the main pressure sensor (Pressure Sensor 1) inside the IPB (Intelligent Power Brake) module. This sensor typically monitors hydraulic pressure in the brake master cylinder or booster chamber, providing critical input for the ABS, ESC, regenerative braking system (RBS), and electric brake assist functions. The IPB ECU sets this fault when the sensor output voltage falls outside the calibrated range (typically 0.5-4.5V), the signal drift rate is abnormal, or the cross-check difference with a redundant sensor (such as Pressure Sensor 2) exceeds the threshold (e.g., a pressure value corresponding to ±0.3V). When this fault occurs, the vehicle may enter brake assist degraded mode (hard brake pedal), limit ESC/ABS functions, disable automatic emergency braking (AEB), and illuminate multiple brake system warning lamps on the instrument cluster.
C057A00›
DTC C057A00 indicates an abnormally high voltage or a short to power (B+) in the IPB (Intelligent Power Brake) internal brake booster temperature sensor power supply circuit. Integrated within the electronic brake booster, this sensor monitors the operating temperature of the booster motor or electronic control unit in real time to prevent brake performance degradation or motor burnout from overheating. The IPB-ECU logs a power supply short circuit fault when the sensor supply line (typically a 5V reference voltage) continuously exceeds the calibrated threshold (generally above 6.0V or reaching the 12V battery voltage). This fault triggers the IPB system safety protection mechanism. It may limit or completely disable brake assist, degrade ABS/ESP functions, and force the vehicle into Limp Home Mode. The system retains only basic unassisted hydraulic braking. This constitutes a severe fault affecting driving safety.
C057F00›
This DTC indicates the IPB (Integrated Power Brake) ECU detects abnormal power supply voltage to the brake booster motor. Conditions include voltage outside the normal range (9-16V), excessive voltage fluctuation, or power supply interruption. The IPB system uses a motor-driven hydraulic pump to replace the conventional vacuum booster. The ECU sets this fault when it detects an open circuit, short circuit, undervoltage (typically <9V), or overvoltage (>16V) in the motor power supply circuit. This fault reduces or disables the brake assist function. The system may enter Limp Home mode, resulting in a hard brake pedal, increased pedal travel, and an illuminated ABS/ESC warning lamp, severely compromising driving safety.
C058200›
DTC C058200 indicates the supply voltage to the brake booster motor inside the IPB (Intelligent Integrated Braking System / One-box electro-hydraulic brake-by-wire system) falls outside the normal operating threshold set by the ECU (typically 9-16V DC). This brushless DC motor drives the brake master cylinder to generate hydraulic brake assist. A generator regulator fault, a power supply circuit short, or reversed polarity during jump-starting can cause high voltage (>16V). A discharged battery, excessive wiring voltage drop, poor ground connection, or internal module DC-DC power supply chip failure can cause low voltage (<9V). This fault triggers the IPB degraded mode, reducing or completely disabling the brake assist function (hard brake pedal). The fault may also inhibit ABS/ESC/EBD functions. In severe cases, the system illuminates the red brake warning lamp, compromising driving safety.
C058800›
DTC C058800 indicates the signal voltage of the brake booster Motor Position Sensor (MPS) inside the Integrated Power Brake (IPB) electro-hydraulic module falls below the ECU threshold (typically below 0.5V or 10% of the reference voltage). The sensor uses electromagnetic or Hall effect principles to monitor the booster motor rotor position in real time, enabling closed-loop control of the motor torque output and brake assist level. When the ECU detects the sensor voltage remains continuously below the calibrated value, it sets a circuit undervoltage fault. This fault prevents the IPB system from accurately determining the motor position, which limits or disables the electric brake assist function. As a result, the vehicle may enter Limp Home Mode, the brake pedal becomes hard, and the ESC/ABS warning lights illuminate.
C058900›
DTC C058900 indicates the IPB (Intelligent Integrated Braking System) electro-hydraulic control module detected a brake booster motor position sensor signal voltage exceeding the calibrated upper limit (typically >4.8V or 95% of the reference voltage). Typically a Hall-effect or electromagnetic position sensor, this component monitors the booster motor rotor position/travel in real time to enable precise electronic brake assist control (similar to a brake-by-wire i-Booster system). Excessively high voltage saturates the signal at the ECU, preventing it from identifying the actual motor position. This triggers fail-safe mode: the system disables the electronic assist function, the brake pedal becomes hard (mechanical backup remains available), and the ABS/ESC/brake system warning lamps illuminate. This is a hard fault; once triggered, it remains active and does not self-clear.
C059400›
DTC C059400 indicates a functional fault in the brake booster motor within the IPB (Intelligent Power Brake) system. This brushless DC motor integrates into the IPB electro-hydraulic module to replace the traditional vacuum booster. It provides electric brake assist based on pedal input and coordinates energy recovery. The IPB control unit sets this code upon detecting abnormal motor current, abnormal speed feedback, a drive circuit fault, or motor mechanical binding. This fault causes a hard brake pedal, reduced brake assist, and increased braking distance. It also degrades or disables functions including ABS, ESC, and Automatic Emergency Braking, severely compromising driving safety.
C058A00›
DTC C058A00 indicates the brake booster motor position sensor (MPS1) in the IPB (Integrated Power Brake, intelligent integrated braking/One-Box brake-by-wire system) outputs a voltage signal outside the valid operating range calibrated by the ECU (typically 0.5V-4.5V). This sensor uses the Hall effect to monitor the absolute angular position of the booster motor rotor in real time and serves as the key feedback component for closed-loop brake boost control. The ECU sets this fault when the signal voltage remains below the lower limit (<0.2V, short to ground or sensor power loss) or above the upper limit (>4.8V, short to power or internal sensor open circuit) for longer than the calibrated time (typically 200ms-500ms). Upon fault detection, the IPB enters a degraded mode. The system cuts off motor assist, requiring the driver to apply greater pedal force (unassisted braking), but retains basic hydraulic braking functions. Simultaneously, the system illuminates the ABS and ESC warning lamps and disables ADAS functions relying on active braking, such as Automatic Emergency Braking (AEB) and Adaptive Cruise Control (ACC).
C058F00›
DTC C058F00 indicates an abnormal coasting regenerative torque signal status in CAN message 0x410 transmitted from the VCU (Vehicle Control Unit) to the IPB (Intelligent Integrated Braking System). In the BYD New Energy architecture, the VCU calculates the target regenerative torque during coasting or braking (typically 0-150 Nm) and transmits it to the IPB via a CAN message. The IPB uses this signal to coordinate motor and hydraulic braking force distribution for energy recovery. This fault indicates the IPB received a regenerative torque signal with a data validation error, an update timeout, or an out-of-range value (such as a negative value or sudden change), or communication synchronization failed between the VCU and IPB. This fault frequently accompanies brake system DTCs such as C055E00 (hydraulic circuit leakage), triggering energy recovery system derating or protective shutdown.
C059000›
This DTC indicates the IPB (Intelligent Power Brake) electro-hydraulic control module detects the brake booster motor drive circuit supply voltage exceeds the calibrated threshold (typically >16V). In BYD DMi models, the 12V low-voltage system powers the IPB, which uses motor direct-drive brake assist (without a vacuum booster). Faults in the DC-DC converter, generator, or IPB internal power management circuit causing voltage increases trigger this DTC. Continuous overvoltage can overheat and damage the IPB internal MOSFETs or motor driver chip. This triggers system protection mode, resulting in a hard brake pedal, reduced brake assist, or restricted ABS/ESC functions. Severe cases force the vehicle into limp mode.
C059100›
This DTC indicates the supply voltage to the IPB (Integrated Power Brake) internal brake booster motor is below the normal operating threshold set by the ECU (typically below 9V or 75% of the nominal value). The IPB system uses a vacuum-free electro-hydraulic assist design. A DC motor drives a hydraulic pump to build brake assist pressure. When motor voltage drops too low, the ECU limits assist torque output to protect hardware. This results in a significantly harder brake pedal, longer pedal travel, and increased braking distance. The IPB internal power management module triggers this fault by monitoring the motor drive circuit voltage in real time. Possible causes include an abnormal external power supply, excessive wiring voltage drop, poor connector contact, or a failed IPB internal DC-DC converter or motor drive circuit. A persistent fault causes the IPB to enter Limp Home mode, limits vehicle speed, and illuminates multiple system warning lights.
C059500›
DTC C059500 indicates an abnormal internal power drive circuit or supply voltage in the IPB (Integrated Power Brake) system. This fault involves abnormal electrical performance of the power management unit (PMU) or DC-DC conversion circuit inside the IPB module, or the external power supply wiring. The IPB controller triggers this DTC when it detects the internal drive voltage exceeds normal thresholds (typically below 9V or above 16V), excessive power supply ripple, or an abnormal internal drive MOSFET/IGBT circuit. This fault can cause vacuum boost simulation failure, a hard brake pedal, energy recovery interruption, and restricted ESC/ABS functions. In severe cases, the vehicle enters limp mode or fails to power up the high-voltage system. This constitutes a critical driving safety fault.
C059592›
The IPB (Intelligent Power Brake) system triggers this DTC when the internal power drive circuit of the Electrical Booster detects an abnormal power supply. The IPB system integrates the conventional vacuum booster, ABS, ESP, and EPB into a single unit, and uses a motor-driven hydraulic system to generate brake assist. DTC C059592 indicates the control module detects the booster motor supply voltage falls outside the normal threshold (typically 9-16V), or the internal DC-DC conversion circuit, power drive MOSFET, or power management chip operates abnormally. This fault disables or limits the electric brake assist function and significantly stiffens the brake pedal (requiring over 200N of pedal force). Simultaneously, the system triggers safety protection mechanisms, restricting ADAS functions such as Autonomous Emergency Braking (AEB) and Adaptive Cruise Control (ACC), severely compromising driving safety.
C059900›
This fault code indicates the EPB (Electronic Parking Brake) control module detects an uncalibrated system, a communication fault, or an actuator fault. Although some repair data categorizes this code under the IPB (Integrated Power Brake) system, C059900 typically indicates interrupted CAN communication between the EPB control unit and the left and right rear parking motors, an unstable power supply, or lost internal module calibration data. When this fault occurs, the EPB control module cannot accurately acquire motor position signals or execute control commands, causing partial or complete electronic parking brake failure. Symptoms include the inability to release or apply the parking brake, and instrument cluster warnings. Extreme cases compromise driving safety.
C05B000›
DTC C05B000 indicates the IPB (Intelligent Integrated Braking System) detects abnormal pressure or a leak in the L2 hydraulic circuit (typically the right-rear/left-rear brake circuit, depending on vehicle brake line routing). The internal IPB hydraulic pressure sensor triggers this fault upon detecting an inability to maintain L2 circuit pressure or an abnormal pressure drop during pressure build-up. The L2 circuit is the second hydraulic circuit in the dual-circuit braking system and controls brake pressure for specific wheels. If the IPB detects a circuit pressure decay rate exceeding the threshold (typically >3-5 bar/s) or a failure to reach target pressure, it records the fault and enters fail-safe mode. This mode limits or disables functions including ABS, ESC, and Automatic Emergency Braking, while retaining basic hydraulic braking capability. This hard fault affects driving safety; clearing the DTC will not resolve the issue.
C05C200›
DTC C05C200 indicates the electric booster motor operating temperature in the IPB (Intelligent Power Brake) integrated brake system exceeds the safety threshold (typically 120°C–130°C). The IPB system uses a brushless DC motor to drive the brake master cylinder and generate hydraulic boost, completely replacing the traditional vacuum booster. When the motor temperature sensor (NTC thermistor) detects an abnormal temperature rise in the motor windings or drive module, the ECU stores this DTC and initiates a protection strategy. This strategy limits motor power output, illuminates the ABS/ESC warning light, and may switch the system to a degraded mode (no boost or hydraulic brake backup). This fault results in a noticeably harder brake pedal, increases required pedal force, and extends braking distance, posing a severe safety hazard during continuous braking or high-speed driving.
C05B001›
DTC C05B001 indicates the IPB (Intelligent Integrated Brake System) detects a leak in brake hydraulic circuit L1. The IPB is the BYD brake-by-wire system (One-Box architecture) integrating brake assist, Electronic Stability Control (ESC), and energy recovery functions. Circuit L1 typically refers to the primary brake circuit or a specific wheel cylinder control circuit (e.g., front left wheel circuit). This fault indicates hydraulic system sealing failure. This condition can extend brake pedal travel, cause a non-linear reduction in braking force output, and restrict or disable active safety functions including ABS, ESC, and Automatic Emergency Braking. Due to braking safety risks, the system illuminates multiple warning lights and may limit vehicle power output.
C05C24B›
The integrated motor drive unit of the IPB (Intelligent Power Brake) electro-hydraulic braking system triggers this DTC. When the internal temperature sensor of the brake assist motor (usually a permanent magnet synchronous motor or brushless DC motor) detects a temperature exceeding the safety threshold (generally 120°C-140°C, depending on software calibration), the ACM (Brake Assist Control Module) records this fault and enables thermal protection mode. In this state, the system may limit or cut off motor assistance, resulting in a noticeably harder brake pedal and longer pedal travel. The driver must build braking force entirely through manual effort. This fault involves functional safety (ISO 26262). The system illuminates the ABS/ESC warning lamp, may disable energy recovery, and forces the vehicle into limp-home mode.
C05CA00›
DTC C05CA00 indicates the IPB (Intelligent Integrated Braking System) electro-hydraulic control module detects the signal voltage from Brake Master Cylinder Piston Position Sensor A exceeds the normal upper limit (typically >4.8V, normal range is 0.5-4.5V). This Hall-effect or potentiometer-type position sensor monitors the travel position of the primary brake master cylinder piston in real time. It provides the IPB ECU with precise pedal depth and hydraulic build-up rate data, enabling regenerative braking, brake assist adjustment, and ESC intervention. High voltage indicates a short to power in the sensor signal circuit, an internal sensor short, an ECU sampling circuit fault, or an abnormally high reference voltage. This fault distorts brake pedal travel recognition, triggers the brake system degraded mode (loss of regenerative braking, pure hydraulic braking), and restricts ABS/ESC functions.
C05CB00›
This DTC indicates the signal voltage from Master Cylinder Piston Position Sensor A, internal to the Intelligent Integrated Brake System (IPB), falls below the calibrated threshold (typically <0.5V or below the valid range lower limit). The sensor uses Hall effect or potentiometer principles to monitor brake master cylinder piston displacement in real time. It provides the IPB control unit with an accurate pedal travel signal to calculate driver braking demand, coordinate electro-hydraulic brake pressure distribution, trigger regenerative braking, and control active safety functions (ESP/ABS/AEB). Low voltage indicates a voltage drop in the sensor supply circuit (5V reference voltage), a signal wire short to ground, an internal sensor short circuit, or a faulty IPB control unit sampling circuit. This fault causes abnormal brake pedal feel, limited or disabled regenerative braking, and degraded ESP/ABS functions. Extreme conditions trigger brake system fail-safe protection (pure hydraulic braking backup), compromising driving safety.
C05CC00›
DTC C05CC00 indicates the master cylinder piston position sensor A signal in the IPB (Integrated Power Brake) exceeds the ECU-calibrated valid range (typically 0.5V-4.5V or the corresponding physical travel range). This Hall effect sensor monitors brake master cylinder piston displacement in real time to calculate driver braking intent, control brake booster motor torque distribution, and coordinate electro-hydraulic blended braking. The IPB module sets this fault when an open circuit, short circuit, or short to power/ground causes the sensor signal voltage to exceed limits, or when actual piston displacement exceeds the physical travel range detectable by the sensor. Upon fault trigger, the vehicle may enter brake backup mode (no assist or limited assist). The system disables regenerative braking, may degrade ABS/ESP functions, and illuminates the brake system warning lamp on the instrument cluster.
C05CD00›
DTC C05CD00 indicates the signal voltage of master cylinder piston position sensor B inside the IPB (Intelligent Integrated Braking System) continuously exceeds the calibrated threshold (typically >4.8V). This Hall-effect position sensor monitors the brake master cylinder piston travel position in real time. It provides the IPB with an accurate brake pedal input signal to enable brake-by-wire assist, coordinated energy recovery, and ESC intervention. This high voltage indicates a short to power in the sensor signal circuit, an internal sensor breakdown short, or an IPB control module sampling circuit fault. This fault forces the IPB into degraded mode, which causes abnormal brake assist (stiff pedal or altered pedal travel), disables the energy recovery system, and limits ESP/ABS functions. In extreme cases, it compromises braking performance. This is a safety-related fault.
C100104›
DTC C100104 has dual definitions across different BYD vehicle platforms. On early pure electric platforms like the E5, this code explicitly indicates an internal CAN hardware communication fault within the ABS control unit. This indicates an abnormality at the physical or data link layer between the ABS module and the vehicle CAN network (powertrain CAN or chassis CAN). The fault can interrupt communication or cause data packet loss in brake-related systems like the ABS, ESP, and EPB. On DM-i and e-Platform 3.0 models like the Song Pro, Tang DM, and Qin Plus, this code typically maps to an abnormal left front wheel speed sensor (WSS) signal or circuit fault. Regardless of the platform, this is a safety-critical braking system fault. The fault degrades or completely disables ABS/ESC functions. The instrument cluster typically illuminates the ABS warning lamp, ESC warning lamp, and parking system fault lamp. CAN hardware faults typically originate from a damaged internal ABS module transceiver, abnormal terminating resistance, or wiring physical layer faults. Wheel speed sensor faults mostly originate from sensor component failure, wiring harness open or short circuits, or an abnormal signal tone ring.
C05CE00›
This DTC indicates the master cylinder piston position sensor B circuit voltage in the IPB (Intelligent Power Brake) smart integrated braking system falls below the calibrated threshold (typically <0.5V). The master cylinder position sensor uses a dual-sensor redundant design (sensors A and B) to monitor brake master cylinder piston displacement in real time. It provides brake pedal travel signals to the IPB ECU to calculate driver braking intent and control electro-hydraulic brake assist. Low sensor B voltage prevents the IPB system from accurately identifying the master cylinder position. This triggers the system safety protection mechanism and limits or disables ESP/ABS functions, potentially causing abnormal brake pedal travel, reduced brake assist, or complete loss of brake assist, seriously compromising driving safety. A short to ground in the sensor power or signal circuit, poor wiring contact, or a damaged sensor typically causes this fault.
C05CF00›
DTC C05CF00 indicates the signal voltage or travel value from Master Cylinder Position Sensor B inside the IPB (Intelligent Integrated Braking System) falls outside the calibrated range (typically 0.5-4.5V or the corresponding physical travel limit). This sensor features a dual-redundant design (Sensors A and B) to monitor brake master cylinder piston displacement in real time, enabling brake pedal travel interpretation, precise brake force distribution, and redundant safety cross-checking. The IPB control unit sets this fault if Sensor B experiences an open circuit, short circuit, mechanical binding, or excessive signal deviation from Sensor A. The fault may cause abnormal brake pedal feel (soft/hard), restricted regenerative braking, ABS/ESC system deactivation, and Automatic Emergency Braking (AEB) failure. In extreme cases, it triggers limp mode (speed-limited driving).
C05D000›
This DTC indicates the signal difference between dual redundant channels A and B of the Master Cylinder Position Sensor inside the IPB (Intelligent Integrated Braking System) exceeds the diagnostic threshold. For functional safety (ISO 26262), the IPB uses a dual-channel redundant design to monitor brake master cylinder piston travel. When the difference between the two signals continuously exceeds the calibrated value (typically 5%-10%), the system determines the sensor signal is implausible. This fault triggers the brake system limp-home mode, potentially causing a loss of electronic brake assist, a hard brake pedal, ABS/ESC deactivation, and illuminating multiple system warning lights.
C05D200›
This fault code indicates an internal pressure sensor monitoring fault within the IPB (Integrated Power Brake). Specifically, during self-test or operation, the IPB control unit detects the voltage signal from the brake master cylinder pressure sensor (or wheel cylinder pressure sensor, depending on configuration) falls below the calibrated normal operating threshold (typically corresponding to an equivalent voltage for a pressure below 0.1-0.3MPa). Potential causes include sensor drift, an open circuit causing signal loss (reading 0V or extremely low voltage), or an internal IPB hydraulic circuit leak preventing actual pressure buildup. This fault triggers the brake system degradation mode and may disable the ABS, ESC, Automatic Emergency Braking (AEB), and energy recovery functions. Extreme conditions may limit vehicle speed and illuminate multiple warning lights.
C05D300›
C05D300 is a specific fault code for the BYD IPB (Intelligent Power Brake) integrated braking system. It indicates the actual hydraulic pressure detected by the master cylinder pressure sensor exceeds the theoretical expected value the ECU calculates using the brake pedal position sensor (master cylinder stroke sensor A/B). This fault represents a logical mismatch between the pressure signal and the pedal stroke signal. Possible causes include: 1) Pressure sensor drift or damage causing a falsely high signal; 2) Incomplete brake master cylinder piston return generating residual pressure; 3) Hydraulic circuit abnormalities (blockage or internal leakage) causing abnormal pressure transfer; 4) Incorrect brake pedal position sensor signals causing the ECU to miscalculate the expected value; 5) IPB control module software algorithm errors. This fault triggers the brake system degraded mode. It may restrict ABS/ESP functions, cause a hard brake pedal or abnormal pedal travel, and severely compromise driving safety.
C05D309›
This DTC indicates the master cylinder pressure sensor built into the IPB (Intelligent Power Brake) electro-hydraulic module detects a pressure signal exceeding the normal upper threshold set by the ECU (typically >25 MPa or signal voltage >4.8 V). In BYD e-Platform 3.0 and DM-i models, the IPB integrates conventional ESP, ABS, and i-BOOSTER functions, and uses a motor-driven plunger pump to build pressure. The pressure sensor monitors master cylinder pressure in real time for brake force distribution, regenerative braking intensity adjustment, and active braking control. When the sensor signal remains above the calibrated value beyond the set time (typically 200-500 ms), the ECU logs a "pressure too high" fault. This fault restricts ABS/ESP functions, disables Automatic Emergency Braking (AEB), and interrupts regenerative braking. In extreme cases, it triggers a "brake system fault" warning and limits vehicle speed. Determine whether the cause is actual excessive hydraulic pressure (such as a blocked brake line) or a false high-pressure signal caused by sensor drift or a short circuit.
C05D500›
This DTC indicates an abnormal open-circuit condition in the Master Cylinder Solenoid Valve or its control circuit within the IPB (Integrated Power Brake) intelligent integrated braking system. In the BYD IPB system, the master cylinder pressure valve controls the hydraulic passage between the brake master cylinder and the wheel cylinders. It serves as a key actuator for electro-hydraulic blended braking control, energy recovery, and ABS/ESC functions. The ECU sets this DTC when it detects an open circuit in the valve drive circuit, abnormal valve position feedback, or a mismatch between the actual and commanded valve states lasting beyond the set threshold (typically exceeding 100ms). This fault reduces brake pressure control accuracy and may trigger a brake system degraded mode (entering pure mechanical backup braking or limiting energy recovery). This condition affects brake pedal feel and active safety functions (such as AEB and ACC).
C080001›
For BYD new energy vehicles (specifically E5, Qin, Tang, and Song models equipped with Bosch or Continental ESP systems), DTC C080001 indicates a fault in the ESP (Electronic Stability Program) lateral acceleration sensor or its power supply circuit. Although the fault description reads "voltage below range", this specifically means the lateral acceleration sensor supply voltage falls below the ECU threshold (normal range: 4.5V–5.5V), or the sensor output signal voltage remains below the valid range (0.5V–4.5V). Consequently, the ECU cannot obtain accurate vehicle lateral acceleration data. This condition causes active safety functions (ESP, ABS, EBD) to fail or enter a degraded mode, severely compromising vehicle stability during cornering or driving on wet and slippery surfaces.
C080002›
This DTC indicates the ABS (Anti-lock Braking System) electronic control unit detects an operating supply voltage outside the calibrated allowable range (typically 9.5V-16V). In the BYD E5, the 12V low-voltage system powers the ABS module. The DC-DC converter steps down voltage from the high-voltage battery pack to provide this supply. If the module detects voltage that is too high (>16V, risking internal ECU circuit damage) or too low (<9V, reducing control accuracy), it logs DTC C080002. This condition may trigger system protection mechanisms, causing ABS, EBD, ESC, and Automatic Emergency Braking functions to fail or enter a degraded mode. Troubleshoot this fault immediately, as it affects braking safety.
C104400›
DTC C104400 indicates the IPB (Integrated Power Brake) system detects an incomplete or insufficient hydraulic brake line bleeding procedure. The IPB system uses internal pressure sensors to monitor the hydraulic pressure build-up characteristics of each brake wheel cylinder. When the system detects air in the lines (abnormal compressibility) or identifies an incorrectly executed bleeding procedure, it triggers this fault code and enters fail-safe mode. This fault restricts ABS/ESP functions, causes abnormal brake pedal travel (spongy pedal), and derates or disables the Automatic Emergency Braking (AEB) function, severely impacting braking safety and driver assistance system performance.
C108008›
C108008 indicates the Hill Hold Control (HHC) system detects an abnormal clutch/start interlock signal. In the BYD E5 battery electric vehicle, this fault does not refer to a conventional mechanical clutch. Instead, it indicates the ABS/ESP control unit fails to receive the correct brake pedal-gear interlock logic signal (the combined signal the system uses to determine if the vehicle is in a 'ready to move off' state). The HHC system relies on the brake switch signal, gear position signal (P/R/N/D status), and wheel speed signals. When the control unit detects a released brake pedal while the gear signal or brake interlock signal contradicts the hill hold release logic, it logs a clutch signal fault. This fault disables the hill start assist function. The vehicle may roll backward on a slope when the driver transitions from the brake pedal to the accelerator pedal. The fault also illuminates the ABS/ESC fault warning lamp and compromises driving safety.
C104C04›
DTC C104C04 indicates a signal failure in the brake pedal position detection switch or internal mode switch within the Integrated Power Brake (IPB) system. In the BYD brake-by-wire architecture, the IPB monitors this switch signal to identify driver braking intent and trigger hydraulic pressure build-up. Switch failure prevents the IPB from accurately identifying pedal travel status, forcing the system into Limp Home mode with limited brake assist. This condition may cause a stiff brake pedal, increased braking distance, and disabled ESC/ABS functions, constituting a severe fault that compromises driving safety.
C106600›
DTC C106600 indicates missing or incorrect Steering Angle Sensor (SAS) calibration data, or that the calibration procedure was never performed. This sensor typically resides within the steering column or ESP control unit and monitors the steering wheel's absolute angle, rotation direction, and angular velocity in real time. It serves as a core input signal for the Electronic Stability Program (ESP/ESC), Electric Power Steering (EPS), and Automatic Emergency Braking (AEB) systems. The system triggers this fault code upon detecting a calibration data validation failure, or a significant deviation between the sensor's output angle and the theoretical zero position during straight-line driving (typically required to be within -5° to +5°). Consequently, the ESP/ESC function enters a degraded or failure mode. This may cause the vehicle to lose skid control during emergency avoidance maneuvers or on slippery roads; however, basic hydraulic braking functions typically remain unaffected.
C108C08›
DTC C108C08 indicates the ABS control unit detects a logic error or implausibility fault in the reverse switch signal (Signal Invalid). In the BYD E5, the HHC (Hill Hold Control) system monitors the reverse signal in real time to determine vehicle travel direction. When the vehicle is in R gear, the reverse switch closes (signal = '1'), and the HHC system activates the hill reverse assist logic. If the ABS module detects a '1' reverse signal while the vehicle moves forward (vehicle speed > 0), or a '0' signal while reversing in R gear, it registers a signal fault. This fault disables the HHC function in reverse mode. The vehicle risks rolling back when reversing on a slope because the system releases braking force prematurely. Simultaneously, the system illuminates the ABS/ESC fault warning lamp, disables specific body stability functions, and enters a safety fallback mode.
C1102›
DTC C1102 indicates the ABS (Anti-lock Braking System) electronic control unit (ECU) detects an operating voltage below the minimum system-calibrated threshold (typically 9V-10.5V, depending on vehicle calibration). This fault indicates an abnormal power supply to the ABS hydraulic modulator assembly, potentially causing active safety systems including ABS, ESP (Electronic Stability Program), EBD (Electronic Brakeforce Distribution), and Automatic Emergency Braking (AEB) to enter a degraded mode or fail completely. In BYD new energy vehicles, this fault typically results from a discharged 12V low-voltage battery, excessive voltage drop in the power supply circuit, high ground circuit resistance, or an internal ABS ECU power management module failure. This critical fault compromises driving safety and requires immediate repair.
C1200›
DTC C1200 indicates the ABS control unit (ECU) detects an electrical integrity fault in the left front wheel speed sensor (WSS) circuit, specifically a short to ground, short to power, or open circuit in the signal line. This sensor is typically a two-wire magnetic or Hall effect type. During normal operation, it transmits either an AC voltage signal proportional to wheel speed (magnetic type, amplitude varying from 0.1V-3V depending on speed) or a square-wave digital signal (Hall effect type) to the ABS ECU. The ECU triggers this code when it detects sensor resistance outside the calibrated range (typically 1.0-1.6kΩ), abnormal signal line voltage (continuous 0V or 12V/B+ voltage), or signal interruption time exceeding the threshold. This fault causes the Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD), Electronic Stability Program (ESP), Traction Control System (TCS), and Autonomous Emergency Braking (AEB) functions to fail or enter a degraded mode. The fault illuminates the ABS, ESP, and tire pressure/brake system warning lights on the instrument cluster, severely compromising vehicle active safety.
C1201›
DTC C1201 indicates the ABS control unit detects that the left front wheel speed sensor signal's rate of change or amplitude exceeds the calibrated threshold. Specifically, the sensor's square-wave output signal exhibits sudden frequency changes, intermittent interruptions, or abnormal voltage fluctuations, preventing the ABS module from accurately calculating the real-time left front wheel speed. This fault can trigger false ABS activation (pump operates without braking input), restrict Electronic Stability Program (ESP) functionality, disable Automatic Emergency Braking (AEB), and in extreme cases, limit power output on some BYD new energy vehicles equipped with torque vectoring control. Classified as a "plausibility fault," it differs from open or short circuit faults by focusing on dynamic signal quality monitoring.
C1202›
DTC C1202 indicates that during continuous monitoring, the ABS/ESC control unit (ECU) detects that the left front wheel speed sensor (WSS) input signal remains at 0 km/h or outputs no pulse signal. In the Bosch/Continental ABS systems of BYD E1/E2/E3/Yuan series models, this code specifically indicates the left front electromagnetic induction or Hall-effect wheel speed sensor fails to transmit a valid square-wave or sine-wave signal to the ECU. This causes the ECU to classify the wheel as "stationary" or "signal missing". This fault triggers the system fail-safe mode, limiting or disabling the Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD), Electronic Stability Control (ESC), Traction Control System (TCS), and Cooperative Regenerative Braking System (CRBS). This severely impacts vehicle stability and braking safety. ISO/SAE standards and some Japanese vehicles (such as Toyota) define C1202 as a brake master cylinder reservoir fluid level fault. However, the fault code system for the specified BYD models clearly maps this code to an abnormal wheel speed sensor signal input.
C1203›
DTC C1203 indicates the ABS detects an electrical fault in the right front wheel speed sensor (WSS) circuit, specifically a signal line short to power/ground or open circuit. The sensor typically uses Hall effect or electromagnetic induction principles, providing pulse signals to the ABS control unit (ECU) to calculate wheel speed. The ECU triggers this fault when it detects a continuously abnormal signal voltage (e.g., 0V or 12V, instead of the normal 0.5-4.5V fluctuation range) or fails to receive pulse signals from the passing tone ring. This causes active safety systems such as ABS, ESC, and EBD to fail or enter a degraded mode. In severe cases, it may affect the coordinated operation of the energy recovery system because the vehicle control system cannot accurately determine the real-time speed and slip ratio of the right front wheel.
C1204›
DTC C1204 indicates the ABS/ESP control unit detected the right front wheel speed sensor output signal change rate (acceleration/deceleration rate) exceeds the configured system threshold (typically ±8-12m/s²). Unlike simple signal loss (C1203) or a static zero signal (C1205), this fault indicates the signal is present but exhibits severe non-linear fluctuations, sudden jumps, or sawtooth distortion. The control unit monitors the wheel speed difference between adjacent sampling cycles to determine if the change is physically plausible (plausibility check). Upon detecting an abnormal jump, the system deems the wheel speed signal unreliable and triggers a degraded protection mode for the ABS, ESP, TCS, EPB, and other systems. This limits or disables related functions to ensure braking safety. Common causes include electromagnetic interference affecting the sensor signal, dynamic gap changes between the sensor and the magnetic encoder, or intermittent failure of the magnetoresistive element inside the sensor.
C1205›
DTC C1205 indicates the ABS/ESC control module continuously detects 0 V (no signal state) from the right front wheel speed sensor. In BYD new energy vehicles, the control module logs an open circuit or sensor failure because the variable reluctance or Hall-effect sensor fails to transmit a valid sine or square wave signal to the ECU. This fault forces the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), Automatic Emergency Braking (AEB), Auto Vehicle Hold (AVH), and energy recovery systems into a degraded or failed mode, and illuminates the ABS/ESC warning lamps on the instrument cluster. Unlike DTC C1204 (excessive signal variation/intermittent fault), C1205 represents a continuous signal loss, typically indicating a hard circuit fault or a damaged sensor.
C1206›
DTC C1206 indicates the ABS control module detected an electrical integrity fault (open or short circuit) in the left rear wheel speed sensor circuit. The sensor is typically a two-wire magnetic inductive or Hall effect type. During normal operation, it sends the ABS module either an AC voltage signal that varies with wheel speed (magnetic inductive type, amplitude increases with speed, approximately 0.1V-5V) or a square-wave digital signal (Hall effect type). The module triggers this fault when it detects infinite resistance in the sensor wiring (open circuit), a short to ground or power, or a continuously abnormal signal voltage (below 0.5V or above 4.5V) exceeding the set threshold (typically 2-5 seconds). This fault causes a loss of the left rear wheel speed signal, forces the ABS, EBD, ESC, TCS, and Automatic Emergency Braking (AEB) systems into a degraded mode, and limits the energy recovery system. In extreme cases, it causes uneven brake force distribution or vehicle skidding.
C1207›
DTC C1207 indicates the torque sensor signal change rate in the Electric Power Steering (EPS) system exceeds the normal threshold. This sensor monitors the magnitude and direction of torque the driver applies to the steering wheel, and steering angle changes. When the sensor signal experiences sudden changes, drift, intermittent interruption, or a change gradient exceeding the calibrated limit, the EPS control unit cannot accurately calculate the required steering assist and triggers fail-safe mode. This fault causes a sudden loss of steering assist, heavy steering, or intermittent assist. In extreme cases, steering wheel binding may occur, severely compromising driving safety. This fault typically illuminates the EPS warning light and may limit vehicle speed.
C120700›
DTC C120700 indicates the hydraulic pump motor inside the IPB (Integrated Power Brake) fails to return to its initial mechanical position (Home Position) within the specified time (typically 200-500 ms) after completing brake boost pressure build-up or an ABS/ESC control action. This fault stems from a malfunction in the motor mechanical return mechanism, Hall position sensor signal feedback, or ECU closed-loop control logic. Upon setting this DTC, the IPB enters Limp Home Mode, resulting in a stiff brake pedal and reduced brake assist. The system disables ABS/ESC active intervention and retains only basic hydraulic braking, severely compromising driving safety.
C2A1700›
DTC C2A1700 indicates the pressure compensation value in the IPB (Intelligent Power Brake) internal hydraulic circuit exceeds the normal ECU-calibrated threshold. Specifically, during pressure holding or build-up in the L1 hydraulic circuit (master cylinder primary circuit or a specific wheel cylinder circuit), the compensation frequency or amount the system requires to maintain target pressure constantly exceeds normal values. Delayed pressure build-up or pressure fluctuations usually accompany this condition. The ECU triggers this fault upon detecting abnormal hydraulic system compressibility (e.g., air ingress) or an internal leak, which forces the system to overwork to maintain pressure. This represents a self-check anomaly within the IPB electro-hydraulic control module. A persistent fault can cause abnormal brake pedal travel, restrict ABS/ESC functions, or disable Automatic Emergency Braking (AEB), posing a driving safety hazard.
C1208›
On BYD E Series and Yuan Series models, DTC C1208 indicates the left rear wheel speed sensor (RLWSS) signal voltage to the ABS/ESP control module is 0V. The control module detects no wheel speed pulse signal for over 100ms, indicating an open circuit, a short to ground, or a failed sensor. The wheel speed signal is a core input parameter for the Anti-lock Braking System (ABS), Electronic Brakeforce Distribution (EBD), Traction Control System (TCS), and Electronic Stability Control (ESC). A missing signal forces these safety systems into fail-safe mode (limp mode), halts their operation, and illuminates multiple warning lights. In generic OBD-II definitions for Bosch ABS systems, C1208 typically indicates "Inlet Valve Coil Rear Circuit Short To Battery". However, some BYD battery electric vehicles redefine this code as a left rear wheel speed sensor signal fault. Consult the vehicle-specific workshop manual during repair.
C1209›
BYD DTC C1209 indicates the ABS system detected an electrical fault in the right rear wheel speed sensor (RR Wheel Speed Sensor) circuit, specifically an open circuit, short to ground, or short to power in the signal line. In new energy vehicles, the wheel speed signal not only controls ABS/ESC braking but also directly affects the motor regenerative braking strategy, driving range calculation, and automatic emergency braking (AEB) function. This fault causes a lost or abnormal right rear wheel speed signal, forcing the ABS into fail-safe mode. This disables anti-lock braking, traction control, and vehicle stability functions, and may trigger regenerative braking derating, creating a safety hazard.
C121208›
DTC C121208 indicates the variant coding stored in the ESP (Electronic Stability Program) control unit mismatches the actual vehicle hardware configuration or contains corrupted data. In BYD new energy vehicles, the ESP hydraulic modulator assembly (integrated ECU) stores model-specific configuration parameters, including key data such as the vehicle platform (E5/Song/Tang, etc.), powertrain type (BEV/PHEV), tire specifications, brake system version, and steering system type. The ESP module triggers this DTC upon detecting abnormal internal variant coding, such as data loss, a checksum failure, or a mismatch with vehicle information on the CAN bus. This software or data configuration fault typically causes no mechanical damage but forces the ESP system into a degraded mode or causes complete failure, compromising vehicle stability control. In extreme cases, ABS/ESP functions become unavailable, though conventional hydraulic braking generally remains unaffected.
C12F909›
DTC C12F909 indicates a blockage or abnormal flow in the internal hydraulic circuit of the IPB (Intelligent Integrated Braking) system. The IPB system integrates the traditional vacuum booster with the ESP and uses a motor-driven hydraulic unit to provide brake boost. The ECU sets this fault when it detects an abnormal pressure difference between the master cylinder and the wheel cylinders, hydraulic pump current exceeding the threshold, or solenoid valve flow deviating from the calibrated value. Potential causes include a blocked brake fluid passage, a sticking solenoid valve, hydraulic pump wear, or internal seal failure. When this fault occurs, the IPB enters a degraded mode that retains basic hydraulic braking but disables energy recovery and automatic emergency braking. Extreme cases may cause a hard brake pedal or increased braking distance.
C2A2000›
DTC C2A2000 indicates that during pressure compensation, IPB (Intelligent Integrated Braking System) hydraulic Circuit C detects a compensation amount exceeding the internal ECU threshold (typically 15–20% above the rated compensation amount). In the BYD One-Box brake-by-wire architecture, "Circuit C" specifically refers to the master cylinder pressure compensation circuit or the high-pressure accumulator maintenance circuit. When the system attempts to maintain or build brake pressure, the ECU logs excessive compensation if it detects an excessively long motor-driven hydraulic pump compensation time, an abnormally high compensation frequency, or a compensation pressure gradient outside the calibrated range. This typically indicates an internal hydraulic circuit leak (poor solenoid valve sealing), abnormal brake fluid compressibility (air ingress or contamination), pressure sensor feedback drift, or reduced hydraulic pump volumetric efficiency. This fault triggers the braking system to enter a degraded mode (backup braking mode), limits ABS/ESC functions, and may increase brake pedal travel and braking distance. This is a Level 2 fault affecting driving safety.
P056023›
This DTC indicates the IPB (Intelligent Integrated Braking System) detected an abnormal main power supply and automatically switched to UBB (Ultracapacitor Backup Battery) power mode to maintain basic braking functions. Common causes include low voltage in the 12V low-voltage system (<9V), poor contact in the power supply circuit, abnormal DC-DC converter output, or an internal IPB power management fault. In this mode, the system limits or disables advanced functions such as ABS, ESC, and Automatic Emergency Braking, retaining only basic hydraulic braking capability. The brake pedal may feel harder. This Level 2 fault affects driving safety.
P056024›
DTC P056024 indicates the IPB (Integrated Power Brake) detects a switch or attempted switch to the UBVR (Unified Backup Voltage Regulator) power supply mode. In the BYD IPB system, the UBVR is the internal backup power management unit. When the main power supply (typically constant 12V power) experiences a voltage drop, instability, or failure, the system triggers a redundant power supply mechanism to maintain critical braking functions. This DTC indicates: 1) abnormal main power supply voltage causing an automatic system switch; 2) a fault in the UBVR switching circuit; 3) an internal power management logic error within the IPB module. This fault may affect functions including ABS, ESC, and Automatic Emergency Braking, risking degraded braking performance.
P056200›
The BYD IPB (Intelligent Power Brake) system logs DTC P056200 for abnormal supply voltage. This code is a manufacturer-specific extension of P0562. The fault indicates the IPB control module detects the 12V system voltage remaining below the normal operating threshold (typically 9.5V-10V, depending on the software version). Because the IPB system uses electro-hydraulic servo braking technology, its motor pump, solenoid valves, and ECU require highly stable voltage. Insufficient voltage causes key safety functions, including the Anti-lock Braking System (ABS), Electronic Stability Control (ESC), and Autonomous Emergency Braking (AEB), to fail or degrade. In DM-i hybrid models, this fault typically relates to an abnormal DC-DC converter (which supplies the 12V system from the high-voltage battery), rather than a traditional alternator failure. This is a safety-critical fault. When triggered, the IPB enters degraded mode and illuminates multiple system warning lights on the instrument cluster.
P056216›
P056216 is a BYD IPB (Intelligent Power Brake) extended fault code. It indicates the IPB control module detects its supply voltage remaining continuously below the internal threshold (typically 9V-10V; normal operating voltage is 12V±0.5V). As the core brake-by-wire component, the IPB provides electro-hydraulic brake assist, coordinates energy recovery, and controls ESC and ABS functions. Insufficient supply voltage reduces brake assist motor torque, causing a stiff brake pedal and extended braking distances. This condition can also degrade or deactivate ESC and ABS functions, severely compromising driving safety. This fault code typically triggers the IPB warning light, the ABS warning light, and a "Please check the braking system" message.
P056300›
DTC P056300 indicates the IPB (Intelligent Power Brake) ECU detects its 12V supply voltage exceeds the system-calibrated safety threshold (typically 16V-18V, depending on vehicle calibration). In BYD DM-i and other new energy vehicles, the IPB system integrates electro-hydraulic brake assist, ESC, ABS, and automatic emergency braking. This fault means the IPB module detects an abnormally high input voltage, which can damage internal solenoid valve coils, motor drive circuits, or sensors. As a result, the system stores the fault code and may enter a degraded protection mode, limiting or disabling ESC/ABS functions. This causes a hard brake pedal and increased braking distance, severely compromising driving safety. Distinguish this code from engine management system DTC P0563: DTC P056300 applies specifically to the IPB system. Typical causes include abnormal DC-DC converter output, IPB internal voltage monitoring circuit faults, or poor circuit grounding.
P060400›
DTC P060400 indicates a read/write checksum error in the RAM (Random Access Memory) of the IPB (Integrated Power Brake) control unit. This fault represents an ECU internal memory integrity self-test failure, indicating the IPB module detected abnormal data storage or retrieval in its internal working memory during the power-on self-test. The IPB uses RAM as the critical storage medium during operation to store temporary variables, fault counters, system status flags, and real-time control parameters. This fault forces the IPB into a degraded mode and may restrict or completely disable the ABS, ESP, Automatic Emergency Braking (AEB), and Electronic Parking Brake (EPB) functions, severely compromising vehicle active safety. Simply clearing the code usually does not resolve this fault; it typically indicates substantial hardware damage or a severe firmware error.
P060500›
DTC P060500 indicates a self-check error in the read-only memory (ROM/Flash) inside the Intelligent Power Brake (IPB) electro-hydraulic control module. This internal control module fault means the IPB ECU detected a checksum error, data corruption, or physical hardware fault during the start-up self-check. This affects the non-volatile memory (typically Flash ROM or EEPROM) storing the brake control program, calibration data, and fault information. The IPB is the core component of the BYD One Box brake-by-wire system. It integrates conventional ABS, ESC (Electronic Stability Control), EPB (Electronic Parking Brake), Automatic Emergency Braking (AEB), and energy recovery functions. A ROM error forces the IPB system into a safety fallback mode (limp home). This mode may fully or partially disable ESC, AEB, and EPB functions, retaining only basic hydraulic braking capability and severely compromising driving safety. Common causes include software corruption, hardware defects, abnormal power loss, electromagnetic interference, or physical memory damage from prolonged high-temperature exposure.
P060600›
In the BYD IPB (Intelligent Power Brake) system, DTC P060600 indicates a self-check failure of the ECU control processor inside the electro-hydraulic brake module. Specifically, the microcontroller unit (MCU) inside the IPB assembly detects a core component failure during the power-on self-test (POST) or runtime monitoring. This indicates an anomaly in the CPU arithmetic unit, internal RAM/ROM, clock oscillator circuit, power supply monitoring circuit, or watchdog reset circuit. The IPB system integrates critical functions including brake boost, Electronic Stability Control (ESC), Anti-lock Braking System (ABS), and regenerative braking force distribution. Consequently, this fault results in a hard brake pedal (loss of electric brake boost), complete failure of ESC/ABS functions, and disabled Automatic Emergency Braking (AEB). In extreme cases, the fault triggers brake system degradation protection and forces the vehicle into limp mode. This constitutes a hardware-level or low-level software fault; clearing the DTC will not resolve the issue.
P060700›
DTC P060700 indicates a functional fault in the internal control processor (MCU/ECU) of the IPB (Intelligent Power Brake). This fault stems from a hardware-level or low-level software abnormality, specifically involving a main control chip calculation error, memory checksum failure, watchdog timeout reset, or internal bus communication interruption. As a core braking component on BYD e-Platform 3.0 and DM-i models, the IPB integrates ESP, ABS, EBD, energy recovery, and brake assist functions. This fault causes brake assist failure (hard brake pedal), loss of ESC/ABS functions, and Automatic Emergency Braking (AEB) deactivation. It may also trigger limp-home mode (speed-limited driving). When this fault occurs, the IPB enters a safety protection state and defaults to pure hydraulic braking. This severe fault compromises driving safety.
P060B00›
DTC P060B00 indicates a performance fault in the A/D (analog-to-digital) conversion control module inside the IPB (Intelligent Power Brake/Integrated Power Brake) system ECU. The IPB ECU uses the A/D converter to acquire real-time analog signals from the brake pedal travel sensor, brake master cylinder pressure sensor, wheel cylinder pressure sensor, motor current sensor, and temperature sensor. It converts these into digital signals for the processor to calculate brake force distribution and regenerative braking coordination. The ECU triggers this DTC if its self-check detects reference voltage drift in the A/D conversion circuit, reduced sampling accuracy, conversion logic errors, or if the internal monitoring circuit detects abnormal A/D conversion timing. This fault forces the braking system into a safety fallback mode (limp mode) and may restrict or disable ABS, ESC, Automatic Emergency Braking (AEB), and parking system functions. This is a brake safety-critical fault.
P060C00›
In the BYD IPB (Integrated Power Brake) system, DTC P060C00 indicates an internal control module main processor performance fault or internal self-test failure. This fault isolates to a calculation error, clock fault, memory checksum failure, or internal bus communication interruption within the core processor (MCU) of the ECU built into the IPB electro-hydraulic module. Because the IPB system integrates key functions including ABS, ESP, EPB, Automatic Emergency Braking (AEB), and energy recovery, this fault can cause brake assist failure, restricted ESC operation, and unavailable AEB, posing serious safety risks. The vehicle typically enters brake system degraded mode (limp mode).
P229900›
P229900 is a BYD-specific fault code for the IPB (Intelligent Integrated Braking System). It indicates a signal logic mismatch between the brake pedal stroke sensor (BPS) and the accelerator pedal stroke sensor (APS), specifically an abnormal zero-point calibration (failure to return to zero). In the IPB system, these two sensor signals must meet interlock logic: when the vehicle is stationary without pedal application, both sensors must simultaneously read zero; during operation, they must meet "brake priority" or "one-pedal" logic. This fault indicates the IPB-ECU detects a non-zero output from the BPS or APS under expected zero-position conditions, or a mismatch in their signal change rates. This fault triggers a safety protection mechanism, potentially causing regenerative braking failure, false Automatic Emergency Braking (AEB) activation, or limited power output (limp mode), severely compromising driving safety.
P25C600›
DTC P25C600 indicates a short to ground in the BLM (Brake Load Module) temperature sensor signal wire inside the IPB (Integrated Power Brake). In the BYD Song PLUS DM-i One-Box braking system, the BLM typically refers to the brake motor or brake fluid temperature monitoring unit. When the ECU detects the temperature signal voltage remaining below the set threshold (near 0V), it identifies a signal wire short to vehicle ground. This fault prevents the IPB from accurately monitoring key component temperatures. To prevent system overheating or degraded braking performance, the ECU triggers a safety protection mode, disables or limits electro-hydraulic brake assist, and illuminates the ABS, ESC, and brake system warning lamps. Because this fault affects a core braking safety function, the system classifies it as a Level 3 severe fault.
U007300›
DTC U007300 indicates a communication failure or Bus-Off condition on the IPB (Intelligent Integrated Braking System / One-Box Integrated Braking System) private CAN bus. As the core control unit of the braking system, the IPB uses the private CAN bus (typically a 500 kbps high-speed CAN) to exchange real-time data with key modules such as the Vehicle Control Unit (VCU), Electronic Stability Control (ESC), Electronic Parking Brake (EPB), and Gateway Module (GWM). This data includes safety-critical information such as wheel speed signals, brake pedal travel, brake force demand, and system status. If the IPB detects its CAN controller has transmitted over 255 consecutive error frames, or detects continuous abnormal dominant or recessive bus levels, a terminating resistor mismatch, or severe signal integrity degradation, it triggers the Bus-Off protection mechanism, stores this DTC, and enters Limp Home mode. The vehicle loses active safety functions such as ABS, ESC, and Automatic Emergency Braking (AEB), retaining only basic hydraulic braking capability. This severe fault compromises driving safety (Severity Level 3).
U010004›
U010004 is an ISO 14229 CAN bus communication fault code. It indicates the ESP (Electronic Stability Program) module detects a data validation error (CRC error), sequence error, or abnormal Data Length Code (DLC) when receiving a CAN data frame from the ECM (Engine Control Module, or the Vehicle Control Unit [VCU] / Motor Control Unit [MCU] in New Energy Vehicles). This compromises data integrity. Unlike U0100 (communication timeout), this fault indicates a physical connection exists but the data content is corrupted. On BYD hybrid and battery electric platforms, this prevents the ESP from obtaining accurate motor torque, speed, or engine operating condition information. This condition can trigger brake system downgrade mode (limiting ABS/ESP functions), disrupt energy recovery and brake coordination control, and in severe cases, cause power interruption or limp mode.
U01000A›
DTC U01000A indicates the Intelligent Integrated Brake System (IPB) or vehicle network detects an integrity check failure or abnormal data content in Engine Control Module (ECM) data packets during CAN communication. Unlike a simple loss of communication (U0100), this fault indicates a normal physical connection where ECM-transmitted data frames contain CRC errors, data overflows, illegal values, or sequence anomalies. Causes include ECM internal memory (RAM/ROM) faults, program runaway, a damaged CAN transceiver, or strong electromagnetic interference. In the DM-i hybrid architecture, abnormal ECM data prevents the IPB from accurately acquiring engine torque, speed, and operating status. This directly affects the brake energy recovery strategy, ABS/ESP coordinated control, and overall vehicle power distribution, posing a safety hazard.
U01000B›
U01000B is a CAN communication fault code for BYD e-Platform 3.0 models (such as the Seal 6 DM-i and Song PLUS DM-i). This fault code indicates the IPB (Integrated Intelligent Braking System) detects a data integrity error when receiving the 0x240 message from the VCU (Vehicle Control Unit). Specific errors include incorrect message byte length, CRC (Cyclic Redundancy Check) errors, non-continuous or abnormal Alive Counter jumps, or key signal values exceeding the valid range. This powertrain CAN network communication fault may limit regenerative braking, cause abnormal electro-hydraulic braking coordination, and in severe cases, trigger the braking system degraded protection mode, compromising driving safety.
U01000C›
DTC U01000C indicates a power CAN bus communication timeout between the IPB (Integrated Intelligent Braking System) and the Front Motor Controller (FMC). Timeout 6 specifically refers to the loss of a specific cyclic message, typically the 0x240 network management message. As the main braking control unit, the IPB requires real-time front motor speed, torque, and temperature data to coordinate the seamless transition between motor regenerative braking and hydraulic mechanical braking. If the communication interruption exceeds the set threshold (typically >100ms), the IPB triggers this fault and enters a degraded mode. This mode disables regenerative braking and may restrict ESC/ABS to basic functions; however, conventional hydraulic braking remains available. This network communication fault may result from an offline Front Motor Controller, a CAN bus physical layer anomaly, or an IPB receiver module failure.
U01000D›
U01000D is a BYD-specific subtype of ISO standard communication fault code U0100 (suffix 0D is a hexadecimal identifier). It indicates a failure to receive a valid data frame via the CAN network between the IPB (Intelligent Power Brake system) and the ECM (Engine Control Module) within a specific cycle (typically 100ms-500ms, depending on calibration). This triggers the timeout counter to reach its threshold (6th timeout). In the DM-i hybrid architecture, the IPB must retrieve real-time engine torque, engine speed, and brake energy regeneration request status from the ECM. Communication interruption degrades the brake energy regeneration function, disables ESC coordinated control, and in severe cases, triggers Limp Home mode. The basic hydraulic braking function remains available.
U010104›
U010104 is a powertrain CAN bus communication fault code indicating the ABS (Anti-lock Braking System) control unit cannot establish normal communication with the TCU (Transmission Control Unit / Motor Control Unit) via the CAN bus. Although the BYD E5 pure electric model uses a fixed-ratio reducer instead of a conventional transmission, the TCU designation typically refers to the drive motor control unit (MCU) or the reducer control module. This fault prevents the ABS system from obtaining real-time powertrain data, such as motor speed, torque output, and gear position status. This data loss restricts regenerative braking and disrupts ESC (Electronic Stability Control) coordination. Severe cases may trigger limp mode or cut power output. Information exchange between the ABS and TCU is critical to vehicle dynamic control; repair this fault immediately.
U010108›
U010108 is a BYD-specific extended fault code and a subclass of the U0101 communication fault series. It indicates the ABS (Anti-lock Braking System) control unit detects a data integrity check failure when receiving CAN messages from the TCU (Transmission/Drive Control Unit; in E5 battery electric vehicles, this typically refers to the motor controller MCU or transmission management unit). Although the ABS module receives the CAN signal from the TCU, the message contains a CRC checksum error, a non-continuous Live Counter, a byte length violating protocol specifications, or out-of-range key signal values (such as motor speed, output torque, or gear status). This prevents the ABS from accurately obtaining real-time powertrain parameters, affecting regenerative braking and ESC (Electronic Stability Control) coordination. In severe cases, the system triggers Limp Home mode and limits motor power to ensure safety.
U011187›
DTC U011187 indicates the Body Control Computer (BCC) failed to receive CAN message ID 0x44A (hexadecimal) from the Battery Management System (BMS) via the air conditioning controller (acting as a gateway/relay node). This battery status information frame typically contains key thermal management parameters, including total battery voltage, total current, SOC, highest/lowest cell voltage, and temperature. This fault represents a gateway communication interruption between the thermal management sub-network and the body control network. The interruption prevents the BCC from obtaining real-time battery status to coordinate thermal management actuators, such as air conditioning compressor speed, PTC heating, and cooling fans. Consequently, this can cause battery temperature control failure, range estimation deviation, or abnormal coordination between the air conditioning system and battery cooling.
U011887›
DTC U011887 is a U-category CAN bus communication fault indicating a subnet communication interruption between the AC Controller and the Battery Cooling Controller (BCC). In the BYD Qin EV300 architecture, the air conditioning system uses an independent CAN subnet. The BCC manages the battery pack liquid cooling system, controlling components such as the battery cooling water pump and the battery cooler three-way valve. The AC Controller requires real-time cooling demand and status information from the BCC to coordinate refrigerant distribution between the cabin air conditioning and the battery cooling system. The AC Controller triggers this DTC when it fails to receive valid CAN messages from the BCC for a continuous period (typically multiple message cycles of 100–200 ms). These messages include IDs containing signals for battery cooling requests, temperature, and flow rate. This fault forces the thermal management system into a degraded mode. This limits battery cooling capacity, which may reduce fast charging speeds or cause battery overheating. The air conditioning system may also forcibly restrict cooling output or enter limp-home protection mode. However, this fault typically does not cause a complete vehicle breakdown.
U012604›
DTC U012604 indicates a CAN bus communication interruption or data frame reception timeout between the Steering Angle Sensor (SAS) and the ABS/ESP control unit. From a network communication perspective, the ESP module logs this fault if it fails to detect a valid CAN message (whose ID typically contains steering angle, angular velocity, and fault status signals) from the SAS within the preset monitoring period (typically 100-200ms). The SAS is the core sensor of the vehicle stability control (ESC/ESP) system, providing driver steering intent information. Communication failure prevents the ESP from calculating the yaw moment correction, triggering system downgrade protection. ESC/ABS functions may completely deactivate or enter limp mode. This failure simultaneously affects ADAS functions relying on the steering angle signal, such as the Electronic Parking Brake (EPB), Automatic Emergency Braking (AEB), and lane keeping. This powertrain CAN (PT-CAN) or chassis CAN (Ch-CAN) network communication fault is typically sporadic and intermittent. Loose wiring connections, electromagnetic interference, or intermittent module lockups commonly cause this issue.
U012608›
DTC U012608 indicates the ABS/ESP control unit receives an abnormal CAN bus data frame or detects a checksum failure from the Steering Angle Sensor (SAS). This fault is a communication data integrity error, not a simple signal timeout. The ABS module flags "corrupted data" when it detects a CRC error in the SAS data packet, an abnormal Data Length Code (DLC), or a signal value outside the physically reasonable range. This fault causes the vehicle's Electronic Stability Program (ESP), Traction Control System (TCS), and Automatic Emergency Braking (AEB) to enter a degraded mode or fail completely. Some models trigger power limitation (limp mode), severely compromising driving safety.
U012E87›
This DTC indicates a data communication interruption between the air conditioning controller (AC ECU) and the electronic fan controller (typically the integrated control module for the condenser fan or radiator fan). In the BYD thermal management system architecture, the AC ECU sends fan speed control commands (based on A/C pressure and coolant temperature) to the electronic fan via the CAN or LIN bus, and receives fan operating status, speed feedback, and fault information. If the communication signal drops continuously for more than the set time threshold (typically 500ms-1s), the system records DTC U012E87. This fault prevents the fan from adjusting speed on demand, potentially reducing A/C cooling efficiency and causing insufficient heat dissipation for the high-voltage system (motor, battery, and power electronics). In extreme cases, the system triggers motor over-temperature protection or limits power output; however, under most operating conditions, the vehicle remains drivable for a short time.
U014008›
DTC U014008 indicates a CAN data communication integrity check failure between the ABS/ESC control unit and the vehicle gateway controller. Data frames sent by the ABS module to the gateway over the Powertrain CAN bus contain CRC errors, out-of-sequence frames, abnormal Data Length Codes (DLC), or protocol format mismatches. Consequently, the gateway determines the received brake system status data is corrupted. This fault triggers the brake system fail-safe strategy, degrading or completely disabling functions such as ABS, ESC, EBD, and Autonomous Emergency Braking (AEB). Simultaneously, the gateway sends multi-system fault warnings to the instrument cluster, severely compromising driving safety.
U0146-00›
DTC U0146-00 indicates a Controller Area Network (CAN) communication interruption between the airbag control unit (SRS ECU) and the vehicle gateway module. In BYD Qin series models, the Body Control Module (BCM) typically integrates the gateway, coordinating data exchange among the powertrain CAN, comfort CAN, and chassis CAN. The system triggers this fault when the SRS fails to receive the gateway handshake signal or data frame within the specified cycle (typically 250ms). This forces the airbag system into a degraded mode, preventing normal airbag deployment, seatbelt pretensioning, or high-voltage cutoff activation during a collision. It may also affect the vehicle’s collision signal recording function. This network communication fault does not involve electrical failures within the SRS components themselves, but it directly disables the passive safety system.
U0146›
DTC U0146 indicates a loss of communication between the airbag control unit (SRS ECU) and the vehicle gateway controller (Gateway Control Module). The gateway acts as the data exchange hub between different vehicle CAN bus networks (such as powertrain CAN, comfort CAN, and chassis CAN) and routes information between control units. When the SRS system cannot communicate with the gateway, the airbag system becomes isolated. It cannot receive critical signals from other systems (such as crash signals, vehicle speed signals, and high-voltage interlock status). Additionally, during a collision, it cannot send commands through the gateway to other systems (such as cutting off the high-voltage power supply, unlocking the doors, and turning on the hazard lights). This may degrade or disable crash protection functions, creating a serious safety hazard.
U014604›
DTC U014604 indicates a CAN communication timeout between the IPB (Integrated Brake Control System) and the Gateway controller. In BYD new energy vehicles, the gateway acts as the core hub of the vehicle CAN network, coordinating data exchange among the Powertrain, Chassis, and Body networks. The IPB system (one-box brake-by-wire solution) retrieves real-time vehicle status information via the gateway (e.g., motor torque, vehicle speed, regenerative braking requests, and VCU coordination commands) while simultaneously transmitting key data, such as brake pedal travel, wheel speed, and braking status, to other systems. When a communication timeout occurs, the IPB enters a degraded protection mode. This can cause regenerative braking failure, limit Electronic Stability Control (ESC) functionality, and cause Automatic Emergency Braking (AEB) to trigger falsely or fail. In severe cases, the instrument cluster illuminates multiple warning lights, including ABS, ESC, and parking system indicators, compromising driving safety.
U014608›
DTC U014608 indicates a CAN communication data length error between the Intelligent Power Brake (IPB) system and the vehicle gateway. In the UDS diagnostic protocol, U0146 indicates abnormal communication with the Body Control Module (BCM) or gateway. The suffix '08' specifically indicates an invalid data frame length or a Bus Off state. This fault occurs when the data packet length sent by the IPB module mismatches the gateway module reception protocol, or when an abnormal CAN physical layer signal causes a data frame parsing failure. Because the IPB controls brake boost, energy recovery, and Electronic Stability Control (ESC), this fault may limit ABS/ESP functions, cause abnormal brake pedal feel, and disable Automatic Emergency Braking (AEB). Severe cases compromise driving safety. When this fault occurs, the vehicle typically enters a degraded mode, limiting specific driver assistance functions.
U014987›
DTC U014987 indicates a communication link interruption between the battery thermal management controller (usually integrated into the Battery Management System (BMS) or a separate thermal management control unit) and the battery thermal circuit electric coolant pump. This pump drives battery coolant circulation and typically uses LIN bus (CAN bus on some models) for digital communication. The controller triggers this fault when it fails to receive pump status feedback signals (such as speed, temperature, or fault status) within a specified period (generally 100-200ms), or when it cannot send control commands (such as target speed requests). This fault forces the battery thermal management system into open-loop control or degraded mode, limiting fast-charging power and power output. Extreme cases may trigger battery high-temperature protection.
U0155-00›
U0155-00 is a CAN bus communication fault code indicating interrupted data communication between the airbag control unit (SRS ECU) and the instrument cluster. In the BYD CAN network architecture, the SRS module transmits airbag status, system fault information, and collision trigger signals in real time to the instrument cluster via the powertrain CAN or body CAN bus. The SRS sets this fault code if it fails to receive a response message from the instrument cluster within the predetermined cycle (usually 250ms-500ms) or detects a bus physical layer fault. This fault may prevent the instrument panel from normally illuminating the SRS fault warning lamp and, in extreme cases, affects the safety warning function during a collision. It classifies as a Level 2 safety-related fault.
U0155›
U0155 is an ISO 15031 CAN bus communication fault code. It indicates a CAN communication interruption between the SRS airbag system (or other vehicle control units) and the instrument cluster control unit (IPC/ICU). In BYD New Energy Vehicles (NEVs), the instrument cluster displays vehicle speed and battery level, and also shows airbag status, fault warning lamps, and seat belt reminders. This fault means the SRS module fails to receive a response message from the instrument cluster within 500ms, or the message checksum fails. A physical layer fault in the Powertrain CAN or Body CAN bus can cause this issue, resulting in a blank instrument cluster display, a continuously illuminated airbag warning lamp, and an abnormal odometer display. In extreme cases, this fault affects normal airbag deployment logic during a collision because the system cannot confirm the instrument cluster warning lamp status.
U016487›
ISO 15031 defines fault code U0164 as 'Lost Communication With HVAC (Air Conditioning Control Module)'. Sub-code 87 is a BYD-specific identifier indicating the BCC (Battery Cooling Controller/Body Control Computer) failed to receive key CAN messages from the air conditioning controller within a 500ms monitoring cycle: ID 0x1DB (ambient temperature, soft shutdown request) or 0x3CF (cabin compressor speed request, A/C request status). This fault indicates a communication interruption between the HVAC sub-network (HVAC-CAN) and the Powertrain CAN or BMS network. This interruption prevents the thermal management system from coordinating the electric compressor, PTC heater, and battery cooling circuit. The system may trigger thermal management derating protection (power limitation or A/C disabled), but typically does not cause immediate vehicle immobilization.
U025387›
U025387 is a U-category network communication DTC. It indicates a CAN bus communication interruption between the Vehicle Control Unit (VCU) or thermal management controller and the Electric Air Conditioning Compressor Controller (ACCM). This fault indicates the main control unit failed to receive valid messages (such as status, speed, and fault data) from the compressor controller within the predetermined cycle (typically 100ms-500ms). This represents a control link communication loss rather than a mechanical failure of the compressor itself. The fault completely disables the air conditioning system (no cooling/heating). This failure subsequently triggers battery thermal management degradation (limiting fast charge power and affecting battery life) and causes insufficient motor cooling (triggering high-temperature protection and power reduction). Severe cases restrict EV functions or prevent the vehicle from starting.
U025487›
U025487 (U0254-87, where 87 is a BYD custom sub-code meaning "signal/information missing or incorrect") indicates interrupted CAN communication between the air conditioning control module (ACU) and the PTC (Positive Temperature Coefficient) heater controller. The PTC is the core high-voltage component of the new energy vehicle heating system (typically operating at 200-750V, 3-6kW). It converts electrical energy into heat, replacing conventional engine waste heat. This fault means the ACU cannot send power regulation commands (PWM or CAN signals) to the PTC or receive PTC feedback regarding high-voltage interlock status, IGBT temperature, operating current, and fault codes. This causes complete failure of the air conditioning heating function (no warm air). In low-temperature environments, this may affect front windshield defrosting and cabin heating, but typically does not affect vehicle drive functions. The communication interruption occurs because the ACU fails to receive a valid CAN frame from the PTC node (Node ID typically in the 0x180-0x1FF range) for 3-5 consecutive message cycles (typically 200-500ms), triggering a timeout.
U025900›
U025900 indicates the IPB (Intelligent Integrated Braking System/Intelligent Power Braking System) failed to receive a valid message or heartbeat signal from the VCU (Vehicle Control Unit) via the powertrain CAN bus within the calibrated time window (typically 100-200ms). In the BYD DM-i hybrid architecture, the VCU acts as the primary vehicle controller. It calculates the regenerative braking torque request in real time and sends it to the IPB. The IPB then coordinates the distribution ratio between electric motor braking and hydraulic braking based on this request. Upon a communication timeout, the IPB determines it has lost communication with the VCU and enters fail-safe/limp-home mode. The IPB forcibly cancels regenerative braking and retains only basic hydraulic brake assist (vacuum or electric assist, depending on the IPB type) while triggering an ABS/ESC system fault warning. This U-category communication fault indicates a network or physical layer connection anomaly rather than a functional failure of the braking actuators. However, it severely impacts regenerative braking efficiency and braking coordination.
U030000›
In the BYD IPB (Intelligent Power Brake) integrated braking system, U030000 indicates the brake control unit (IPB ECU) internal software is incompatible with the vehicle network configuration. Specifically, the IPB module software version number, Calibration Verification Number (CVN), or configuration word (Coding) does not match the vehicle VCU, Gateway, and other CAN nodes. This prevents the brake control strategy from loading normally or causes verification failure. The fault triggers the system safety protection mechanism, restricting regenerative braking, Automatic Emergency Braking (AEB), and ESC functions. Severe cases cause a hard brake pedal, limit brake assist, or force the vehicle into limp mode. This functional fault compromises driving safety.
U040100›
U040100 is a U-class network communication fault code indicating "Invalid data received from Engine Control Module (ECM)". In the BYD DM-i hybrid architecture, the IPB (Intelligent Integrated Brake System) receives real-time parameters from the ECM via the powertrain CAN bus—including engine speed, output torque, and operating status—to coordinate the distribution ratio between regenerative and mechanical braking. If the IPB detects an ECM data frame checksum error, data outside the physically reasonable range, a communication protocol version mismatch, or a data update timeout, it logs "ECM data corrupted" and stores this fault code. This fault can force the IPB into a degraded mode, resulting in regenerative braking failure, restricted ESC function, and abnormal brake pedal feel. In extreme cases, it triggers a "Brake System Fault" warning and limits vehicle power output, severely compromising driving safety.
U043204›
DTC U043204 indicates a communication timeout between the IPB (Intelligent Integrated Braking System) control unit and the MMx_TX module (Multi-axis Acceleration Sensor). The MMx module monitors the vehicle’s lateral and longitudinal acceleration, providing critical dynamic data for ESP, Automatic Emergency Braking (AEB), Electronic Brakeforce Distribution (EBD), and the brake energy recovery system. The IPB main control unit triggers this fault if it fails to receive valid acceleration data within the specified communication cycle (usually 200 ms), or if the received data frame contains a checksum error or abnormal length. The system enters a safety fallback mode, limiting or disabling advanced functions such as ESP and AEB. The vehicle usually retains basic hydraulic braking, allowing cautious driving to a repair facility.
U043208›
DTC U043208 indicates a private CAN network communication fault in the IPB (Intelligent Power Brake) system. Specifically, the IPB control unit detects an integrity check failure when receiving data frames from the MMx_TX module (Inertial Measurement Unit, IMU). This fault involves data link layer errors, including received byte length mismatching the DBC definition (expected 8 bytes, actual length abnormal), Cyclic Redundancy Check (CRC) errors, Alive Counter discontinuity or abnormal jumps, and signal values exceeding the physically valid range (e.g., lateral acceleration >4g or yaw rate >300°/s). The IMU provides vehicle lateral acceleration, longitudinal acceleration, and yaw rate signals, serving as the core sensor for ESC (Electronic Stability Control), ABS (Anti-lock Braking System), and AEB (Automatic Emergency Braking). This fault prevents the IPB from obtaining accurate vehicle body attitude data and triggers the brake system degraded protection mode. Symptoms include restricted ESC function, altered ABS intervention logic, or disabled Automatic Emergency Braking. The system usually retains basic hydraulic braking functions.
U055A00›
U055A00 is a CAN bus communication protocol layer fault code. It indicates the IPB (Intelligent Integrated Braking System/One-Box) detects that the data frame length (DLC) of a received VCU (Vehicle Control Unit) CAN message does not match the specified protocol, or the data payload length check fails. This network communication data link layer error means the VCU transmitted an abnormal message structure (e.g., sending 6 bytes instead of the protocol-specified 8 bytes, or using incorrect padding bytes). In Song PLUS DMi models, the VCU and IPB communicate via the chassis CAN or powertrain CAN to transmit key signals such as vehicle speed, torque request, and regenerative braking level. If the data length is incorrect, the IPB cannot correctly interpret the vehicle status. This can trigger braking system downgrade protection, limit ESC, ABS, and regenerative braking functions, and severely compromise driving safety.
U058504›
U058504 indicates a private CAN or powertrain CAN communication timeout fault between the IPB (Intelligent Integrated Braking System) and the TCU (Transmission Control Unit). In the BYD DM-i architecture, the IPB requires real-time key data from the TCU, including motor torque, vehicle speed, gear position, and regenerative braking requests, to coordinate brake force distribution and regenerative braking. The IPB triggers this fault if it fails to receive a valid data frame from the TCU within a 500ms monitoring period (normal message cycle is 10-20ms), or if it receives data checksum errors for more than 10 consecutive frames. This fault disables the regenerative braking function and forces the ESC/ABS into degraded mode. In extreme cases, it triggers the powertrain Limp Home mode, limiting vehicle speed.
U058508›
DTC U058508 indicates abnormal CAN communication data between the IPB (Intelligent Integrated Braking System) and the TCU (Transmission Control Unit). Specifically, the TCU data frames received by the IPB contain checksum errors, implausible data logic, or communication timeouts. This fault affects critical data exchange between the powertrain and braking systems. The TCU cannot provide the IPB with accurate gear state, torque request, motor speed, or vehicle speed signals, preventing the braking system from coordinating the switching logic between energy recovery and hydraulic braking. Potential causes include corrupted internal TCU EEPROM data, CAN bus physical layer interference, logic errors resulting from an abnormal TCU power supply, or parsing errors at the IPB receiver. When triggered, this fault may limit vehicle power output, disable the energy recovery function, and illuminate the ABS/ESC warning light. In severe cases, the vehicle enters Limp Home Mode.
U100004›
DTC U100004 indicates the control module detects the CAN bus is in a "Bus Off" state. In the BYD E5 battery electric vehicle, the ABS system reports this DTC. It indicates the ABS control unit CAN controller automatically shuts down communication due to an error counter overflow (typically caused by continuous bus errors or interference) to protect the bus from a faulty node. Consequently, the ABS module cannot exchange data with the vehicle network (including the gateway, VCU, and instrument cluster). This disables functions such as the anti-lock braking system and electronic stability control (ESC) and illuminates multiple instrument panel warning lamps. On some other models (such as the S6), U100004 may also indicate a transmission control module (TCU) communication fault, but the core mechanism remains a communication interruption between the control unit and the CAN bus.
U100308›
This DTC indicates abnormal communication between the EPB (Electronic Parking Brake) control module and the vehicle chassis CAN network (Chassis CAN). Technical details: 1) The EPB module fails to receive valid data frames from the ABS/ESP, VCU, or gateway module within the preset monitoring period (typically 100ms), triggering a timeout counter overflow; 2) Received CAN messages fail the CRC check, contain an abnormal Data Length Code (DLC), or trigger a Bus-Off state. On the BYD E5, the EPB system relies on the CAN bus to receive the vehicle speed signal (from the ABS), brake pedal status, gear position information, and power mode signal. Communication interruption causes the EPB auto-release/Auto Vehicle Hold (AVH) function to fail. Extreme cases may trigger Limp Home mode, though the system usually retains the mechanical emergency release function. This fault belongs to the chassis network communication category. Prioritize inspecting the physical layer wiring.
U1004-00›
DTC U1004-00 indicates a short to ground in the CAN bus communication circuit of the BYD vehicle's airbag system (SRS). In the BYD Qin series network architecture, the SRS ECU communicates in real time with the vehicle control unit, instrument cluster, and other modules via the CAN bus (typically powertrain CAN or body CAN). If either CAN_H (high line, usually orange/black) or CAN_L (low line, usually orange/brown) shorts to body ground (GND) due to damaged insulation, water corrosion, or mechanical damage, the short pulls the differential bus signal voltage low and prevents normal transmission of communication messages. This fault forces the SRS system into fail-safe mode, illuminates the airbag warning lamp on the instrument cluster, and prevents proper coordination between the seat belt pretensioners, crash sensors, and airbag deployment circuits. This creates a severe safety hazard where the airbags fail to deploy during a collision.
U1005-00›
DTC U1005-00 indicates a short circuit between the Supplemental Restraint System (SRS) Controller Area Network (CAN) communication line and vehicle power (+B). In BYD Qin series models, the Airbag Control Module (ACM) communicates with the vehicle network via the CAN bus. When the CAN-H or CAN-L line shorts to constant power or ignition power, the short pulls the bus voltage up to 12V (battery voltage), distorting the CAN signal and interrupting communication. This prevents the airbag system from receiving crash sensor signals or triggering airbag deployment, and may affect safety-related functions such as the seat belt pretensioners and the airbag warning lamp. Because the CAN bus uses differential signal transmission, a short to power disrupts communication across the entire CAN network segment (typically including the instrument cluster and BCM). This serious fault endangers driving safety.
U1004›
In BYD new energy vehicles, DTC U1004 typically indicates "loss of communication with the Vehicle Control Unit (VCU)" or "powertrain CAN bus off". Some SRS system documentation defines it as "CAN short to ground". This fault indicates a physical layer abnormality in the Controller Area Network (CAN) communication bus. Specifically, the insulation resistance to ground for CAN-H (high line) or CAN-L (low line) decreases or shorts completely. This pulls the bus differential signal voltage down to ground potential, preventing normal data frame transmission. Consequently, this interrupts communication between the VCU or airbag control unit and other key vehicle modules, such as the Battery Management System (BMS), Motor Control Unit (MCU), and Instrument Cluster Unit (ICU). The interruption triggers the fault protection mechanism, forcing the vehicle into limp mode (speed limited to 20-40 km/h) or inhibiting the Ready state, severely compromising driving safety. In the SRS system, this fault also disables passive safety systems such as the airbags and seat belt pretensioners.
U1005›
DTC U1005 indicates the vehicle SRS (Supplemental Restraint System/airbag system) control module detects a short circuit between its CAN communication bus (including CAN-H and/or CAN-L lines) and the vehicle positive power supply (12V battery voltage or high-voltage system power supply). Normally, the CAN bus voltage to ground measures approximately 2.5V (recessive state) and 3.5V/1.5V (dominant state). A short to power pulls the CAN bus voltage up to 12V, completely interrupting communication between the SRS system and the vehicle Powertrain CAN or Body CAN. Because safety-critical subsystems (airbag system, seat belt pretensioners, crash sensors, and seat occupancy detection) rely on the CAN bus for data exchange and trigger command transmission, this fault prevents the airbag system from deploying normally during a collision. This constitutes a Level 1 severe fault affecting occupant life safety.
U1332-00›
DTC U1332-00 indicates the airbag control unit (SRS ECU) receives an abnormal or timed-out vehicle speed signal via the body CAN bus (B-CAN). This fault occurs when the SRS module fails to receive a valid vehicle speed data frame from the instrument cluster or ABS/ESP module within the predetermined cycle, preventing the airbag system from determining collision severity based on real-time vehicle speed. This safety system communication fault compromises the collision safety strategy, potentially causing airbag deployment timing deviations during high-speed collisions or false deployments during low-speed collisions.
U2ABC16›
DTC U2ABC16 indicates the electric air conditioning compressor high-voltage load circuit detects an input voltage below the normal operating threshold (typically below 420VDC). In the 2019 BYD Qin EV thermal management system, the high-voltage battery pack (nominally 500V+) powers the electric compressor through the high-voltage power distribution box. This fault indicates the compressor controller detects insufficient bus voltage to maintain normal compressor startup or operation during self-check or running. This fault triggers a protective compressor shutdown, causing air conditioning cooling failure. In extreme cases, it may affect battery thermal management (liquid cooling system), but typically does not directly cause a vehicle breakdown. The root cause involves an abnormality in the high-voltage power supply circuit, Battery Management System (BMS) voltage monitoring, or the compressor controller internal voltage sampling circuit.
U1332›
DTC U1332 indicates the airbag control unit (SRS ECU) receives an abnormal or interrupted vehicle speed signal via the CAN bus. In BYD new energy vehicles, the ESP electronic stability system (or IPB intelligent integrated braking system) typically generates the vehicle speed signal and transmits it to the SRS module via the chassis CAN or powertrain CAN bus. The SRS system relies on the vehicle speed signal for crash algorithm decisions: at low speeds, it may trigger only the seat belt pretensioners without deploying the airbags, while at high speeds, it requires multi-stage airbag coordination. CAN bus communication interruptions, signal source module failures, or SRS module receiving circuit faults trigger this code. This fault causes the airbag system to enter a degraded mode, which may prevent correct deployment during a collision or cause the warning lamp to remain illuminated.
U2ABB17›
DTC U2ABB17 indicates the electric compressor controller (PCU) detects the input DC high voltage exceeds the permitted operating threshold (typically 110%-120% of the rated voltage). For example, on the 2019 Qin EV, the system triggers this fault when the high-voltage battery pack voltage exceeds approximately 420-450V or the compressor internal bus voltage reading exceeds the safe range. This fault acts as a high-voltage safety protection mechanism for the thermal management system. Upon detecting abnormally high voltage, the compressor actively disconnects the high-voltage relay to protect the IGBT power module and motor insulation. Actual battery pack overvoltage, voltage sampling circuit drift, high-voltage interlock circuit faults, or control software logic errors can cause this fault. Determine whether the condition is a genuine voltage abnormality or a signal detection fault.